Patent Publication Number: US-2022215473-A1

Title: Trading orders with decaying reserves

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation of U.S. patent application Ser. No. 16/927,009 filed Jul. 13, 2020 which is a continuation of U.S. patent application Ser. No. 16/578,890 filed Sep. 23, 2019 (now U.S. Pat. No. 10,713,724 issued on Jul. 14, 2020), which is continuation of U.S. patent application Ser. No. 14/280,119 filed May 16, 2014 (now U.S. Pat. No. 10,453,132 issued on Oct. 22, 2019), which is a continuation of U.S. patent application Ser. No. 13/620,794 filed Sep. 15, 2012 (now U.S. Pat. No. 8,732,053 issued on May 20, 2014), which is a continuation of Ser. No. 13/100,137, filed May 3, 2011 (now U.S. Pat. No. 8,346,642 issued on Jan. 1, 2013), which is a continuation of U.S. patent application Ser. No. 12/780,178, filed May 14, 2010 (now U.S. Pat. No. 7,937,308 issued on May 3, 2011), which is a continuation of U.S. patent application Ser. No. 12/603,544, filed Oct. 21, 2009 (now U.S. Pat. No. 7,747,498 issued on Jun. 29, 2010), which is a continuation-in-part application of U.S. patent application Ser. No. 12/106,494, filed Apr. 21, 2008 (now U.S. Pat. No. 7,716,122 issued on May 11, 2010). The disclosures of the above-referenced patents and patent applications are hereby incorporated by reference herein in their entireties. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  illustrates a system according to at least one embodiment of the systems disclosed herein. 
       FIG. 2  illustrates decay of a trading order with a reserved quantity, according to certain embodiments. 
       FIG. 3  illustrates decay of a trading order with a reserved quantity, according to certain embodiments. 
       FIG. 4  illustrates a flowchart for managing a trading order with a reserved quantity, according to certain embodiments. 
    
    
     DETAILED DESCRIPTION 
     The following sections I-X provide a guide to interpreting the present application. 
     I. Terms 
     The term “product” means any machine, manufacture and/or composition of matter, unless expressly specified otherwise. 
     The term “process” means any process, algorithm, method or the like, unless expressly specified otherwise. 
     Each process (whether called a method, algorithm or otherwise) inherently includes one or more steps, and therefore all references to a “step” or “steps” of a process have an inherent antecedent basis in the mere recitation of the term ‘process’ or a like term. Accordingly, any reference in a claim to a ‘step’ or ‘steps’ of a process has sufficient antecedent basis. 
     The term “invention” and the like mean “the one or more inventions disclosed in this application”, unless expressly specified otherwise. 
     The terms “an embodiment”, “embodiment”, “embodiments”, “the embodiment”, “the embodiments”, “one or more embodiments”, “some embodiments”, “certain embodiments”, “one embodiment”, “another embodiment” and the like mean “one or more (but not all) embodiments of the disclosed invention(s)”, unless expressly specified otherwise. 
     The term “variation” of an invention means an embodiment of the invention, unless expressly specified otherwise. 
     A reference to “another embodiment” in describing an embodiment does not imply that the referenced embodiment is mutually exclusive with another embodiment (e.g., an embodiment described before the referenced embodiment), unless expressly specified otherwise. 
     The terms “including”, “comprising” and variations thereof mean “including but not necessarily limited to”, unless expressly specified otherwise. Thus, for example, the sentence “the portfolio includes a red widget and a blue widget” means the portfolio includes the red widget and the blue widget but may include something else. 
     The term “consisting of” and variations thereof means “including and limited to”, unless expressly specified otherwise. Thus, for example, the sentence “the portfolio consists of a red widget and a blue widget” means the portfolio includes the red widget and the blue widget but does not include anything else. 
     The term “compose” and variations thereof means “to make up the constituent parts of, component of, or member of”, unless expressly specified otherwise. Thus, for example, the sentence “the red widget and the blue widget compose a portfolio” means the portfolio includes the red widget and the blue widget. 
     The term “exclusively compose” and variations thereof means “to make up exclusively the constituent parts of, to be the only components of or to be the only members of”, unless expressly specified otherwise. Thus, for example, the sentence “the red widget and the blue widget exclusively compose a portfolio” means the portfolio consists of the red widget and the blue widget, and nothing else. 
     The terms “a”, “an” and “the” mean “one or more”, unless expressly specified otherwise. 
     The term “plurality” means “two or more”, unless expressly specified otherwise. 
     The term “herein” means “in the present application, including anything which may be incorporated by reference”, unless expressly specified otherwise. 
     The phrase “at least one of”, when such phrase modifies a plurality of things (such as an enumerated list of things) means any combination of one or more of those things, unless expressly specified otherwise. For example, the phrase “at least one of a widget, a car and a wheel” means either (i) a widget, (ii) a car, (iii) a wheel, (iv) a widget and a car, (v) a widget and a wheel, (vi) a car and a wheel, or (vii) a widget, a car and a wheel. The phrase “at least one of”, when such phrase modifies a plurality of things does not mean “one of” each of the plurality of things. 
     Numerical terms such as “one”, “two”, etc. when used as cardinal numbers to indicate quantity of something (e.g., one widget, two widgets), mean the quantity indicated by that numerical term, but do not mean at least the quantity indicated by that numerical term. For example, the phrase “one widget” does not mean “at least one widget”, and therefore the phrase “one widget” does not cover, e.g., two widgets. 
     The phrase “based on” does not mean “based only on”, unless expressly specified otherwise. In other words, the phrase “based on” describes both “based only on” and “based at least on”. The phrase “based at least on” is equivalent to the phrase “based at least in part on”. 
     The term “represent” and like terms are not exclusive, unless expressly specified otherwise. For example, the term “represents” does not mean “represents only”, unless expressly specified otherwise. In other words, the phrase “the data represents a credit card number” describes both “the data represents only a credit card number” and “the data represents a credit card number, and the data also represents something else”. 
     The term “whereby” is used herein only to precede a clause or other set of words that express only the intended result, objective or consequence of something that is previously and explicitly recited. Thus, when the term “whereby” is used in a claim, the clause or other words that the term “whereby” modifies do not establish specific further limitations of the claim or otherwise restricts the meaning or scope of the claim. 
     The term “e.g.” and like terms mean “for example”, and thus does not limit the term or phrase it explains. For example, in the sentence “the computer sends data (e.g., instructions, a data structure) over the Internet”, the term “e.g.” explains that “instructions” are an example of “data” that the computer may send over the Internet, and also explains that “a data structure” is an example of “data” that the computer may send over the Internet. However, both “instructions” and “a data structure” are merely examples of “data”, and other things besides “instructions” and “a data structure” can be “data”. 
     The term “respective” and like terms mean “taken individually”. Thus if two or more things have “respective” characteristics, then each such thing has its own characteristic, and these characteristics can be different from each other but need not be. For example, the phrase “each of two machines has a respective function” means that the first such machine has a function and the second such machine has a function as well. The function of the first machine may or may not be the same as the function of the second machine. 
     The term “i.e.” and like terms mean “that is”, and thus limits the term or phrase it explains. For example, in the sentence “the computer sends data (i.e., instructions) over the Internet”, the term “i.e.” explains that “instructions” are the “data” that the computer sends over the Internet. 
     Any given numerical range shall include whole and fractions of numbers within the range. For example, the range “1 to 10” shall be interpreted to specifically include whole numbers between 1 and 10 (e.g., 1, 2, 3, 4, . . . 9) and non-whole numbers (e.g., 1.1, 1.2, . . . 1.9). 
     Where two or more terms or phrases are synonymous (e.g., because of an explicit statement that the terms or phrases are synonymous), instances of one such term/phrase does not mean instances of another such term/phrase must have a different meaning. For example, where a statement renders the meaning of “including” to be synonymous with “including but not limited to”, the mere usage of the phrase “including but not limited to” does not mean that the term “including” means something other than “including but not limited to”. 
     II. Determining 
     The term “determining” and grammatical variants thereof (e.g., to determine a price, determining a value, determine an object which meets a certain criterion) is used in an extremely broad sense. The term “determining” encompasses a wide variety of actions and therefore “determining” can include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” can include resolving, selecting, choosing, establishing, and the like. 
     The term “determining” does not imply certainty or absolute precision, and therefore “determining” can include estimating, extrapolating, predicting, guessing and the like. 
     The term “determining” does not imply that mathematical processing must be performed and does not imply that numerical methods must be used and does not imply that an algorithm or process is used. 
     The term “determining” does not imply that any particular device must be used. For example, a computer need not necessarily perform the determining. 
     III. Forms of Sentences 
     Where a limitation of a first claim would cover one of a feature as well as more than one of a feature (e.g., a limitation such as “at least one widget” covers one widget as well as more than one widget), and where in a second claim that depends on the first claim, the second claim uses a definite article “the” to refer to the limitation (e.g., “the widget”), this does not imply that the first claim covers only one of the feature, and this does not imply that the second claim covers only one of the feature (e.g., “the widget” can cover both one widget and more than one widget). 
     When an ordinal number (such as “first”, “second”, “third” and so on) is used as an adjective before a term, that ordinal number is used (unless expressly specified otherwise) merely to indicate a particular feature, such as to distinguish that particular feature from another feature that is described by the same term or by a similar term. For example, a “first widget” may be so named merely to distinguish it from, e.g., a “second widget”. Thus, the mere usage of the ordinal numbers “first” and “second” before the term “widget” does not indicate any other relationship between the two widgets, and likewise does not indicate any other characteristics of either or both widgets. For example, the mere usage of the ordinal numbers “first” and “second” before the term “widget” (1) does not indicate that either widget comes before or after any other in order or location; (2) does not indicate that either widget occurs or acts before or after any other in time; and (3) does not indicate that either widget ranks above or below any other, as in importance or quality. In addition, the mere usage of ordinal numbers does not define a numerical limit to the features identified with the ordinal numbers. For example, the mere usage of the ordinal numbers “first” and “second” before the term “widget” does not indicate that there must be no more than two widgets. 
     When a single device, article or other product is described herein, more than one device/article (whether or not they cooperate) may alternatively be used in place of the single device/article that is described. Accordingly, the functionality that is described as being possessed by a device may alternatively be possessed by more than one device/article (whether or not they cooperate). 
     Similarly, where more than one device, article or other product is described herein (whether or not they cooperate), a single device/article may alternatively be used in place of the more than one device or article that is described. For example, a plurality of computer-based devices may be substituted with a single computer-based device. Accordingly, the various functionality that is described as being possessed by more than one device or article may alternatively be possessed by a single device/article. 
     The functionality and/or the features of a single device that is described may be alternatively embodied by one or more other devices which are described but are not explicitly described as having such functionality/features. Thus, other embodiments need not include the described device itself, but rather can include the one or more other devices which would, in those other embodiments, have such functionality/features. 
     IV. Disclosed Examples and Terminology are not Limiting 
     Neither the Title (set forth at the beginning of the first page of the present application) nor the Abstract (set forth at the end of the present application) is to be taken as limiting in any way as the scope of the disclosed invention(s), is to be used in interpreting the meaning of any claim or is to be used in limiting the scope of any claim. An Abstract has been included in this application merely because an Abstract is required under 37 C.F.R. § 1.72(b). 
     The title of the present application and headings of sections provided in the present application are for convenience only and are not to be taken as limiting the disclosure in any way. 
     Numerous embodiments are described in the present application and are presented for illustrative purposes only. The described embodiments are not, and are not intended to be, limiting in any sense. The presently disclosed invention(s) are widely applicable to numerous embodiments, as is readily apparent from the disclosure. One of ordinary skill in the art will recognize that the disclosed invention(s) may be practiced with various modifications and alterations, such as structural, logical, software, and electrical modifications. Although particular features of the disclosed invention(s) may be described with reference to one or more particular embodiments and/or drawings, it should be understood that such features are not limited to usage in the one or more particular embodiments or drawings with reference to which they are described, unless expressly specified otherwise. 
     Though an embodiment may be disclosed as including several features, other embodiments of the invention may include fewer than all such features. Thus, for example, a claim may be directed to less than the entire set of features in a disclosed embodiment, and such claim would not include features beyond those features that the claim expressly recites. 
     No embodiment of method steps or product elements described in the present application constitutes the invention claimed herein, or is essential to the invention claimed herein, or is coextensive with the invention claimed herein, except where it is either expressly stated to be so in this specification or expressly recited in a claim. 
     The preambles of the claims that follow recite purposes, benefits and possible uses of the claimed invention only and do not limit the claimed invention. 
     The present disclosure is not a literal description of all embodiments of the invention(s). Also, the present disclosure is not a listing of features of the invention(s) which must be present in all embodiments. 
     All disclosed embodiments are not necessarily covered by the claims (even including all pending, amended, issued and canceled claims). In addition, an embodiment may be (but need not necessarily be) covered by several claims. Accordingly, where a claim (regardless of whether pending, amended, issued or canceled) is directed to a particular embodiment, such is not evidence that the scope of other claims do not also cover that embodiment. 
     Devices that are described as in communication with each other need not be in continuous communication with each other, unless expressly specified otherwise. On the contrary, such devices need only transmit to each other as necessary or desirable and may actually refrain from exchanging data most of the time. For example, a machine in communication with another machine via the Internet may not transmit data to the other machine for long period of time (e.g. weeks at a time). In addition, devices that are in communication with each other may communicate directly or indirectly through one or more intermediaries. 
     A description of an embodiment with several components or features does not imply that all or even any of such components/features are required. On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the present invention(s). Unless otherwise specified explicitly, no component/feature is essential or required. 
     Although process steps, algorithms or the like may be described or claimed in a particular sequential order, such processes may be configured to work in different orders. In other words, any sequence or order of steps that may be explicitly described or claimed does not necessarily indicate a requirement that the steps be performed in that order. The steps of processes described herein may be performed in any order possible. Further, some steps may be performed simultaneously despite being described or implied as occurring non-simultaneously (e.g., because one step is described after the other step). Moreover, the illustration of a process by its depiction in a drawing does not imply that the illustrated process is exclusive of other variations and modifications thereto, does not imply that the illustrated process or any of its steps are necessary to the invention(s), and does not imply that the illustrated process is preferred. 
     Although a process may be described as including a plurality of steps, that does not imply that all or any of the steps are preferred, essential or required. Various other embodiments within the scope of the described invention(s) include other processes that omit some or all of the described steps. Unless otherwise specified explicitly, no step is essential or required. 
     Although a process may be described singly or without reference to other products or methods, in an embodiment the process may interact with other products or methods. For example, such interaction may include linking one business model to another business model. Such interaction may be provided to enhance the flexibility or desirability of the process. 
     Although a product may be described as including a plurality of components, aspects, qualities, characteristics and/or features, that does not indicate that any or all of the plurality are preferred, essential or required. Various other embodiments within the scope of the described invention(s) include other products that omit some or all of the described plurality. 
     An enumerated list of items (which may or may not be numbered) does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. Likewise, an enumerated list of items (which may or may not be numbered) does not imply that any or all of the items are comprehensive of any category, unless expressly specified otherwise. For example, the enumerated list “a computer, a laptop, a PDA” does not imply that any or all of the three items of that list are mutually exclusive and does not imply that any or all of the three items of that list are comprehensive of any category. 
     An enumerated list of items (which may or may not be numbered) does not imply that any or all of the items are equivalent to each other or readily substituted for each other. 
     All embodiments are illustrative, and do not imply that the invention or any embodiments were made or performed, as the case may be. 
     V. Computing 
     It will be readily apparent to one of ordinary skill in the art that the various processes described herein may be implemented by, e.g., appropriately programmed general purpose computers, special purpose computers and computing devices. Typically a processor (e.g., one or more microprocessors, one or more microcontrollers, one or more digital signal processors) will receive instructions (e.g., from a memory or like device), and execute those instructions, thereby performing one or more processes defined by those instructions. Instructions may be embodied in, e.g., one or more computer programs, one or more scripts. 
     A “processor” means one or more microprocessors, central processing units (CPUs), computing devices, microcontrollers, digital signal processors, or like devices or any combination thereof, regardless of the architecture (e.g., chip-level multiprocessing/multi-core, RISC, CISC, Microprocessor without Interlocked Pipeline Stages, pipelining configuration, simultaneous multithreading). 
     Thus a description of a process is likewise a description of an apparatus for performing the process. The apparatus that performs the process can include, e.g., a processor and those input devices and output devices that are appropriate to perform the process. 
     Further, programs that implement such methods (as well as other types of data) may be stored and transmitted using a variety of media (e.g., computer readable media) in a number of manners. In some embodiments, hard-wired circuitry or custom hardware may be used in place of, or in combination with, some or all of the software instructions that can implement the processes of various embodiments. Thus, various combinations of hardware and software may be used instead of software only. 
     The term “computer-readable medium” refers to any medium, a plurality of the same, or a combination of different media, that participate in providing data (e.g., instructions, data structures) which may be read by a computer, a processor or a like device. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks and other persistent memory. Volatile media include dynamic random access memory (DRAM), which typically constitutes the main memory. Transmission media include coaxial cables, copper wire and fiber optics, including the wires that comprise a system bus coupled to the processor. Transmission media may include or convey acoustic waves, light waves and electromagnetic emissions, such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read. 
     Various forms of computer readable media may be involved in carrying data (e.g. sequences of instructions) to a processor. For example, data may be (i) delivered from RAM to a processor; (ii) carried over a wireless transmission medium; (iii) formatted and/or transmitted according to numerous formats, standards or protocols, such as Ethernet (or IEEE 802.3), SAP, ATP, Bluetooth□, and TCP/IP, TDMA, CDMA, and 3G; and/or (iv) encrypted to ensure privacy or prevent fraud in any of a variety of ways well known in the art. 
     Thus a description of a process is likewise a description of a computer-readable medium storing a program for performing the process. The computer-readable medium can store (in any appropriate format) those program elements which are appropriate to perform the method. 
     Just as the description of various steps in a process does not indicate that all the described steps are required, embodiments of an apparatus include a computer/computing device operable to perform some (but not necessarily all) of the described process. 
     Likewise, just as the description of various steps in a process does not indicate that all the described steps are required, embodiments of a computer-readable medium storing a program or data structure include a computer-readable medium storing a program that, when executed, can cause a processor to perform some (but not necessarily all) of the described process. 
     Where databases are described, it will be understood by one of ordinary skill in the art that (i) alternative database structures to those described may be readily employed, and (ii) other memory structures besides databases may be readily employed. Any illustrations or descriptions of any sample databases presented herein are illustrative arrangements for stored representations of information. Any number of other arrangements may be employed besides those suggested by, e.g., tables illustrated in drawings or elsewhere. Similarly, any illustrated entries of the databases represent exemplary information only; one of ordinary skill in the art will understand that the number and content of the entries can be different from those described herein. Further, despite any depiction of the databases as tables, other formats (including relational databases, object-based models and/or distributed databases) could be used to store and manipulate the data types described herein. Likewise, object methods or behaviors of a database can be used to implement various processes, such as the described herein. In addition, the databases may, in a known manner, be stored locally or remotely from a device which accesses data in such a database. 
     Various embodiments can be configured to work in a network environment including a computer that is in communication (e.g., via a communications network) with one or more devices. The computer may communicate with the devices directly or indirectly, via any wired or wireless medium (e.g. the Internet, LAN, WAN or Ethernet, Token Ring, a telephone line, a cable line, a radio channel, an optical communications line, commercial on-line service providers, bulletin board systems, a satellite communications link, a combination of any of the above). Each of the devices may themselves comprise computers or other computing devices, such as those based on the Intel® Pentium® or Centrino™ processor, that are adapted to communicate with the computer. Any number and type of devices may be in communication with the computer. 
     In an embodiment, a server computer or centralized authority may not be necessary or desirable. For example, the present invention may, in an embodiment, be practiced on one or more devices without a central authority. In such an embodiment, any functions described herein as performed by the server computer or data described as stored on the server computer may instead be performed by or stored on one or more such devices. 
     Where a process is described, in an embodiment the process may operate without any user intervention. In another embodiment, the process includes some human intervention (e.g., a step is performed by or with the assistance of a human). 
     VI. Continuing Applications 
     The present disclosure provides, to one of ordinary skill in the art, an enabling description of several embodiments and/or inventions. Some of these embodiments and/or inventions may not be claimed in the present application but may nevertheless be claimed in one or more continuing applications that claim the benefit of priority of the present application. 
     Applicants intend to file additional applications to pursue patents for subject matter that has been disclosed and enabled but not claimed in the present application. 
     VII. 35 U.S.C. § 112, paragraph 6 
     In a claim, a limitation of the claim which includes the phrase “means for” or the phrase “step for” means that 35 U.S.C. § 112, paragraph 6, applies to that limitation. 
     In a claim, a limitation of the claim which does not include the phrase “means for” or the phrase “step for” means that 35 U.S.C. § 112, paragraph 6 does not apply to that limitation, regardless of whether that limitation recites a function without recitation of structure, material or acts for performing that function. For example, in a claim, the mere use of the phrase “step of” or the phrase “steps of” in referring to one or more steps of the claim or of another claim does not mean that 35 U.S.C. § 112, paragraph 6, applies to that step(s). 
     With respect to a means or a step for performing a specified function in accordance with 35 U.S.C. § 112, paragraph 6, the corresponding structure, material or acts described in the specification, and equivalents thereof, may perform additional functions as well as the specified function. 
     Computers, processors, computing devices and like products are structures that can perform a wide variety of functions. Such products can be operable to perform a specified function by executing one or more programs, such as a program stored in a memory device of that product or in a memory device which that product accesses. Unless expressly specified otherwise, such a program need not be based on any particular algorithm, such as any particular algorithm that might be disclosed in the present application. It is well known to one of ordinary skill in the art that a specified function may be implemented via different algorithms, and any of a number of different algorithms would be a mere design choice for carrying out the specified function. 
     Therefore, with respect to a means or a step for performing a specified function in accordance with 35 U.S.C. § 112, paragraph 6, structure corresponding to a specified function includes any product programmed to perform the specified function. Such structure includes programmed products which perform the function, regardless of whether such product is programmed with (i) a disclosed algorithm for performing the function, (ii) an algorithm that is similar to a disclosed algorithm, or (iii) a different algorithm for performing the function. 
     Where there is recited a means for performing a function that is a method, one structure for performing this method includes a computing device (e.g., a general-purpose computer) that is programmed and/or configured with appropriate hardware to perform that function. 
     Also included is a computing device (e.g., a general-purpose computer) that is programmed and/or configured with appropriate hardware to perform that function via other algorithms as would be understood by one of ordinary skill in the art. 
     VIII. Disclaimer 
     Numerous references to a particular embodiment do not indicate a disclaimer or disavowal of additional, different embodiments, and similarly references to the description of embodiments which all include a particular feature do not indicate a disclaimer or disavowal of embodiments which do not include that particular feature. A clear disclaimer or disavowal in the present application shall be prefaced by the phrase “does not include” or by the phrase “cannot perform”. 
     IX. Incorporation By Reference 
     Any patent, patent application or other document referred to herein is incorporated by reference into this patent application as part of the present disclosure, but only for purposes of written description and enablement in accordance with 35 U.S.C. § 112, paragraph 1, and should in no way be used to limit, define, or otherwise construe any term of the present application, unless without such incorporation by reference, no ordinary meaning would have been ascertainable by a person of ordinary skill in the art. Such person of ordinary skill in the art need not have been in any way limited by any embodiments provided in the reference 
     Any incorporation by reference does not, in and of itself, imply any endorsement of, ratification of, or acquiescence in any statements, opinions, arguments or characterizations contained in any incorporated patent, patent application or other document, unless explicitly specified otherwise in this patent application. 
     X. Prosecution History 
     In interpreting the present application (which includes the claims), one of ordinary skill in the art shall refer to the prosecution history of the present application, but not to the prosecution history of any other patent or patent application, regardless of whether there are other patent applications that are considered related to the present application, and regardless of whether there are other patent applications that share a claim of priority with the present application. 
     In recent years, electronic trading systems have gained widespread acceptance for trading of a wide variety of items, such as goods, services, financial instruments, and commodities. For example, electronic trading systems have been created which facilitate the trading of financial instruments and commodities such as stocks, bonds, currency, futures contracts, oil, and gold. 
     Many of these electronic trading systems use a bid/offer process in which bids and offers are submitted to the systems by a passive side and then those bids and offers are hit or lifted (or taken) by an aggressive side. For example, a passive trading counterparty may submit a “bid” to buy a particular trading product. In response to such a bid, an aggressive side counterparty may submit a “hit” in order to indicate a willingness to sell the trading product to the first counterparty at the given price. Alternatively, a passive side counterparty may submit an “offer” to sell the particular trading product at the given price, and then the aggressive side counterparty may submit a “lift” (or “take”) in response to the offer to indicate a willingness to buy the trading product from the passive side counterparty at the given price. 
     In some embodiments, a system comprises a memory operable to store a trading order for a particular quantity of a trading product, wherein a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity. The system further comprises a processor communicatively coupled to the memory and operable to disclose the displayed quantity to one or more market centers. The processor is further operable to identify a decay rate associated with the trading order. The processor is further operable to cause the reserved quantity to decay based at least in part on the identified decay rate. 
     Various embodiments of the present disclosure may benefit from numerous advantages. It should be noted that one or more embodiments may benefit from some, none, or all of the advantages discussed below. 
     One advantage is that a trading system may allow a trader to submit a trading order comprising a displayed quantity and a reserved quantity. The trading system may disclose the displayed quantity to multiple market centers while preventing the disclosure of the reserved quantity. In some embodiment, the trading system causes the reserved quantity of the trading order to decay over time. The trading system may thereby reduce certain risks associated with market volatility. In particular, by causing the reserved quantity to decay, the trading system may reduce the trader&#39;s risk of having exposure for a stale trading order with a price that is no longer favorable for the trader. 
     Another advantage is that, by causing the reserved quantity of trading order to decay, the trading system may improve system efficiency. In particular, as trading orders with reserved quantities are not aggressed, trading system may gradually delete the reserved quantities of such trading orders from one or more order books. Deleting portions of such trading orders may free up memory and processing resources in the trading system. Trading system may thereby improve data throughput and/or conserve system resources. 
     A system comprises a memory operable to store a trading order for a particular quantity of a trading product, wherein a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity. The system further comprises a processor communicatively coupled to the memory and operable to disclose the displayed quantity to one or more market centers. The processor is further operable to identify a decay rate associated with the trading order. The processor is further operable to cause the reserved quantity to decay based at least in part on the identified decay rate. 
       FIG. 1  illustrates one embodiment of a trading system  10 . Generally, trading system  10  comprises a trading platform  50  communicatively coupled to clients  20 , networks  30 , and market centers  40 . Trading platform  50  may receive and process trading orders  12  from traders  70 . In some embodiments, trading platform  50  may cause a portion of trading order  12  to decay over time. Trading platform  50  may thereby reduce certain risks associated with market volatility. In particular, by causing a portion of trading order  12  to decay, trading platform  50  may reduce the risks of having exposure to a stale trading order  12  with a price that has become unfavorable. 
     A given trading order  12  may comprise two parts—a “displayed quantity” and a “reserved quantity.” In placing trading order  12 , trader  70  may indicate that only a portion of the total quantity of trading order  12  should be displayed to other traders  70 . This portion of trading order  12  to be displayed to other traders  70  is referred to as the “displayed quantity.” The remaining portion of trading order  12  is referred to as the “reserved quantity.” Designating a portion of trading order  12  as a “reserved quantity” allows trader  70  to enter a large trading order  12  while only displaying a portion of that trading order  12  to other traders  70 . Trading platform  50  may incrementally fill a particular trading order  12  by first filling the displayed quantity of that trading order  12  and then using the reserved quantity to replenish the displayed quantity of that trading order  12 . 
     Trading orders  12  generally comprise orders  12   a  and counterorders  12   b . Orders  12   a  and counterorders  12   b  may be buy orders  14  and sell orders  16 . Orders  12   a  and counterorders  12   b  are complementary actions such as, for example, buying and selling. If an order  12   a  refers to a buy order  14 , then a counterorder  12   b  refers to a sell order  16 . Conversely, if an order  12   a  refers to a sell order  16 , then a counterorder  12   b  refers to a buy order  14 . A buy order  14  is a request to buy a particular quantity of a particular trading product (e.g., bid request). A sell order  16  is a request to sell a particular quantity of a particular trading product (e.g., offer request). In particular embodiments, trading order  12  may specify a target price (e.g., target bid price or target offer price) for the trading product. Although system  10  is exemplified below using equities as the trading product, the trading product that forms the basis of trading order  12  may comprise any type of goods, services, financial instruments, commodities, any other suitable product or combination of products. Examples of financial instruments include, but are not limited to, stocks, bonds, futures contracts, fixed income securities, interest rate derivatives, currencies, debentures, options, securities, derivative trading instruments, etc. 
     Clients  20  are operable to receive trading orders  12  from traders  70  and to send trading orders  12  to trading platform  50  and/or market centers  40 . Clients  20  comprise any suitable local or remote end-user devices that may be used by traders  70  to access one or more elements of trading system  10 , such as trading platform  50 . A particular client  20  may comprise a computer, workstation, telephone, Internet browser, electronic notebook, Personal Digital Assistant (PDA), pager, or any other suitable device (wireless or otherwise), component, or element capable of receiving, processing, storing, and/or communicating information with other components of system  10 . Client  20  may also comprise any suitable user interface such as a display, microphone, keypad, keyboard, touch screen, or any other appropriate terminal equipment according to particular configurations and arrangements. It will be understood that there may be any number of clients  20  communicatively connected to trading platform  50 . In addition, there may be any number of clients  20  communicatively connected to market centers  40  without using trading platform  50 . 
     Although clients  20  are described herein as being used by “traders”  70 , it should be understood that the term “trader” is meant to broadly apply to any user of trading system  10 , whether that user is an agent acting on behalf of a principal, a principal, an individual, a legal entity (such as a corporation), or any machine or mechanism that is capable of placing and/or responding to trading orders  12  in system  10 . 
     According to certain embodiments, traders  70  may include market makers. A market maker may include any individual or firm that submits and/or maintains either or both bid and offer trading orders  12  simultaneously for the same instrument. For example, a market maker may include an individual or firm, such as a brokerage or bank, that maintains either a firm bid and/or offer price in a given security by standing ready, willing, and able to buy and/or sell that security at publicly quoted prices. A market maker generally displays bid and/or offer prices for specific numbers of specific securities, and if these prices are met, the market maker will immediately buy for and/or sell from its own accounts. According to certain embodiments, a single trading order  12  may be filled by a number of market makers at potentially different prices. 
     Networks  30  are communication platforms operable to exchange data or information between clients  20  and trading platform  50  and/or market centers  40 . According to certain embodiments, a particular network  30  may represent an Internet architecture which provides clients  20  with the ability to communicate trading or transaction information to trading platform  50  and/or market centers  40 . According to certain embodiments, network  30  comprises a plain old telephone system (POTS), which traders  70  may use to perform the same operations and functions. Transactions may be assisted by a broker associated with trading platform  50  or manually keyed into a telephone or other suitable electronic device to request that a transaction be executed. In certain embodiments, network  30  may be any packet data network (PDN) offering a communications interface or exchange between any two nodes in system  10 . Network  30  may comprise any combination of local area network (LAN), metropolitan area network (MAN), wide area network (WAN), wireless local area network (WLAN), virtual private network (VPN), intranet, or any other appropriate architecture or system that facilitates communications between clients  20  and trading platform  50  and/or market centers  40 . 
     Market centers  40  comprise all manner of order execution venues including exchanges, Electronic Communication Networks (ECNs), Alternative Trading Systems (ATSs), market makers, or any other suitable market participants. Each market center  40  maintains a bid and offer price for a given trading product by standing ready, willing, and able to buy or sell that trading product at publicly quoted prices, also referred to as market center prices. Different market centers  40  may provide different market center prices for particular trading products. For example, a particular market center  40  may offer a particular bid price and/or offer price for a particular trading product, while another market center  40  may offer a different bid price and/or offer price for the same trading product. A particular market center  40  may charge a transaction cost to execute trading orders  12  that remain in the order books of that market center  40  for more than a certain length of time. Different market centers  40  may have different policies regarding the disclosure of various details of trading orders  12 . For example, certain market centers  40  referred to as “cooperative” market centers may disclose both the displayed quantities and the reserved quantities of trading orders  12  to trading platform  50 . Other market centers  40  referred to as “non-cooperative” market centers may disclose only the displayed quantities of trading orders  12  to trading platform  50 . 
     Trading platform  50  is a trading architecture that facilitates the routing, matching, and otherwise processing of trading orders  12 . Trading platform  50  may comprise a management center or a headquartering office for any person, business, or entity that seeks to route, allocate, match, process, or fill trading orders  12 . Accordingly, trading platform  50  may include any suitable combination of hardware, software, personnel, devices, components, elements, or objects that may be utilized or implemented to achieve the operations and functions of an administrative body or a supervising entity that manages or administers a trading environment. In certain embodiments, trading platform  50  comprises client interface  52 , market interface  54 , processor  56 , and memory module  60 . 
     Client interface  52  of trading platform  50  is communicatively coupled to network  30  and supports communications between clients  20  and the various components of trading platform  50 . According to certain embodiments, client interface  52  comprises a transaction server that receives trading orders  12  communicated by clients  20  via network  30 . 
     Market interface  54  is communicatively coupled to market centers  40  and supports communications between market centers  40  and the various components of trading platform  50 . Market interface  54  may comprise a transaction server that receives trading orders  12  communicated by market centers  40 . Market interface  54  may be operable to send to market centers  40  trading orders  12  received from clients  20  connected directly to trading platform  50 . 
     Client interface  52  and market interface  54  are communicatively coupled to processor  56 . Processor  56  is operable to record trading orders  12  in memory module  60  and route trading orders  12  to market centers  40 . Processor  56  is further operable to execute logic  62  stored in memory module  60  to match buy orders  14  and sell orders  16  received by client interface  52  and market interface  54 . In addition, processor  56  is operable to incrementally fill a particular trading order  12  by using the reserved quantity of that trading order  12  to replenish the displayed quantity of that trading order  12 . In some embodiments, processor  56  may cause the reserved quantity of trading order  12  to decay over time. Processor  56  may comprise any suitable combination of hardware and software implemented in one or more modules to provide the described function or operation. 
     For example, processor  56  may cause the reserved quantity of trading order  12  to decay over time in accordance with decay rule  66 . Decay rule  66  may be stored in memory module  60 . The trading order  12  may include decay rule  66 . Decay rule  66  may be embedded within trading order  12 . Decay rule  66  may be part of a data signal that includes trading order  12 . Processor  56  may retrieve decay rule  66  from the trading order  12  and store decay rule  66  in memory module  60 . Processor  56  may process trading order  12  and decay rule  66  (e.g., included in trading order  12 ) without storing decay rule  66  in memory module  60 . 
     Memory module  60  comprises any suitable arrangement of random access memory (RAM), read only memory (ROM), magnetic computer disk, CD-ROM, or other magnetic or optical storage media, or any other volatile or non-volatile memory devices that store one or more files, lists, tables, or other arrangements of information such as trading orders  12 . Although  FIG. 1  illustrates memory module  60  as internal to trading platform  50 , it should be understood that memory module  60  may be internal or external to components of trading system  10 , depending on particular implementations. Also, memory module  60  illustrated in  FIG. 1  may be separate or integral to other memory devices to achieve any suitable arrangement of memory devices for use in trading system  10 . 
     According to certain embodiments, memory module  60  stores logic  62  and trader profiles  64 . Logic  62  generally comprises software instructions for routing, matching, processing, or filling trading orders  12 . Processor  56  is operable to execute logic  62  in memory module  60  to match buy orders  14  and sell orders  16  and to determine the priority of traders  70  associated with those buy orders  14  and sell orders  16 . 
     Memory module  60  may store a respective trader profile  64  for each trader  70  in trading system  10 . Trader profile  64  for a particular trader  70  may comprise the name, account information, trading preferences, trade history, and/or other suitable information associated with the particular trader  70 . In some embodiments, trader profile  64  comprises one or more decay rules  66 . 
     The trading order  12  may include decay rule  66 . Decay rule  66  may be embedded within trading order  12 . Decay rule  66  may be part of a data signal that includes trading order  12 . A trading order  12  may include one or more decay rules  66 . 
     Processor  56  may execute decay rule  66  (e.g., stored in memory module  60  and/or specified by trading order  12  as described above) to determine the rate and/or frequency at which to reduce the reserved quantity of trading order  12 . Decay rule  66  may specify an amount by which the reserved quantity of trading order  12  should decay over time. For example, decay rule  66  may direct processor to reduce the reserved quantity of trading order  12  by one thousand units per minute. By reducing the reserved quantity of trading order  12  over time, processor may reduce the risks associated with having a stale trading order  12  in a volatile market. In some embodiments, a particular decay rule  66  may be associated with a decay interval  68  and a decay rate  72  (described below with respect to  FIG. 2 ). 
     It should be understood that the internal structure of trading platform  50  and the interfaces, processors, and memory devices associated therewith is malleable and can be readily changed, modified, rearranged, or reconfigured in order to achieve the intended operations of trading platform  50 . 
     In operation, trading platform  50  is operable to receive trading order  12  from client  20 . Trading order  12  may be for a particular quantity of a particular trading product (e.g., equities, commodities, futures, currencies, bonds, and so forth). In some embodiments, trading order  12  designates a portion of the particular quantity as a displayed quantity. Trading order  12  may designate another portion of the particular quantity of trading order  12  as the reserved quantity. Trading platform  50  may disclose the displayed quantity of trading order  12  to market center  40 . In some embodiments, trading platform  50  prevents the disclosure of the reserved quantity of trading order  12  to market center  40 . 
     Upon receiving trading order  12 , processor  56  may identify decay rule  66  stored in memory module  60 . Decay rule  66  may instruct processor  56  to reduce the reserved quantity of trading order  12  over time. Reducing the reserved quantity of trading order  12  may comprise deleting a portion of trading order  12  from one or more order books  74  in memory module  60 . In some embodiments, the reduction of the reserved quantity of trading order  12  is based at least in part on decay rate  72  associated with decay rule  66 . 
     In addition to specifying displayed and reserved quantities of a particular trading product, trading order  12  (or, e.g., a data signal that includes or accompanies trading order  12 ) may specify a decay rule  66 . Thus, the trading order  12  may include decay rule  66 . Decay rule  66  may be embedded within trading order  12 . Trading order  12  may store decay rule  66 . Decay rule  66  may be part of a data signal that includes trading order  12 . A trading order  12  may include one or more decay rules  66 . 
     The decay rule  66  (e.g., included in trading order  12 ) may specify, e.g., a decay interval, a decay rate, and/or a decay quantity. The trading order  12  may specify, e.g., a decay interval, decay rate, and/or a decay quantity in addition to a decay rule  66 . 
     Although decay rule(s)  66 , decay interval(s)  68 , and decay rate(s)  72  are shown in  FIG. 1  as being stored in the trading platform  50  in memory module  60 , any of decay rule(s)  66 , decay interval(s)  68 , and decay rate(s)  72 , etc., may be included in trading order  12 . Any subsequent description of, e.g., processor  56  retrieving a decay rule  66  from memory module  60  is merely an example, and processor  56  may instead, or in addition, retrieve a decay rule  66  from trading order  12 . 
     Thus, upon receiving trading order  12 , processor  56  may identify decay rule  66  stored in memory module  60 . Upon receiving trading order  12 , processor  56  may retrieve, e.g., decay rule  66  from trading order  12 . Processor  56  may store, e.g., decay rule  66  in memory module  60 . Processor  56  may update decay rule  66  in memory module  60  based on a decay rule stored in trading order  12 . Upon receiving trading order  12 , processor  56  may process trading order  12  and, e.g., any associated decay rule  66  without storing, e.g., the decay rule  66  in memory module  60 . 
     In some embodiments, upon receiving trading order  12 , processor  56  may retrieve a decay rule  66  from memory module  60  and may retrieve specific values or inputs, e.g., any of a decay interval, a decay rate, a decay quantity, etc., from trading order  12 . That is, trading order  12  may include a particular value of decay interval  68 , decay rate  72 , and/or a decay quantity. Processor  56  may receive the trading order  12  and may retrieve one or more specific values (e.g., decay rate  72 ) from trading order  12 , and execute a decay rule  66  stored in memory module  60  using these values. 
       FIG. 2  is a table  200  that sets forth an example illustrating the decay of trading order  12 , according to certain embodiments. In this example, one or more decay rules  66  (e.g., stored in memory module  60  and/or specified by trading order  12  as described above) cause the reserved quantity of trading order  12  to decay over time. As each successive interval of time expires, processor  56  may reduce the reserved quantity of trading order  12  by a configurable increment. The time intervals at which the reserved quantity decays may be referred to as decay intervals  68 . The rate at which the reserved quantity decays may be referred to as decay rate  72 . For example, decay rule  66  may specify that, at the expiration of each successive minute after trading platform  50  receives trading order  12 , processor  56  reduces reserved quantity of trading order  12  by five million units. In this example, decay interval  68  is one minute and decay rate  72  is five million units/minute. Although the foregoing example illustrates decay interval  68  of one minute, it should be understood that decay interval  68  may be ten seconds, two minutes, ten minutes, and/or any suitable interval of time. Although the foregoing example illustrates decay rate  72  of five million units/minute, it should be understood that decay rate  72  may be one hundred units/second, one million units/minute, and/or any suitable rate. 
     In some embodiments, once processor  56  uses counterorder  12   b  to fill the displayed quantity of order  12   a , processor  56  may replenish the displayed quantity of order  12   a . In particular, processor  56  may be configured to use a portion of the reserved quantity of order  12   a  to replenish the displayed quantity of order  12   a . In some embodiments, the filling and replenishing of the displayed quantity of order  12   a  occurs independently of the decay of the reserved quantity of order  12   a.    
     The example order  12   a  in table  200  illustrates certain embodiments. In this example, trading platform  50  comprises decay rule  66  (and/or, e.g., trading order  12  specifies decay rule  66 ) to reduce the reserved quantity of trading order  12  by twenty million units per minute. In this example, at 10:26:02 a.m., trading platform  50  receives Bid A from Trader A. Bid A is for one hundred million units of Security X at a price of two dollars per unit. The trading product and price associated with Bid A is illustrated in columns  202  and  204 , respectively. Bid A has a displayed quantity of ten million units and a reserved quantity of ninety million units. The displayed quantity and reserved quantity of Bid A is illustrated in columns  206  and  208 , respectively. 
     Upon receiving Bid A, processor  56  discloses the displayed quantity (i.e., ten million units) of Bid A to market centers  40 . At 10:26:34 a.m., trading platform  50  receives Offer B, a matching counterorder  12   b . Offer B is for ten million units of Security X at two dollars per unit. Upon receiving Offer B, processor  56  uses the ten million units from Offer B to fill the displayed quantity of Bid A. Processor  56  then uses ten million units from the reserved quantity of Bid A to replenish the displayed quantity of Bid A. Thus, the reserved quantity of Bid A becomes eighty million units. 
     In this example, trading platform  50  does not receive any other matching counterorders  12   b  prior to 10:27:02 a.m.—one minute after trading platform  50  received Bid A. According to decay rule  66 , at 10:27:02 a.m., processor  56  reduces reserved quantity of Bid A from eighty million units to sixty million units. With the expiration of each successive minute, processor  56  continues to reduce reserved quantity of Bid A according to decay rule  66 . By decaying the reserved quantity of Bid A over time, processor  56  may reduce certain risks associated with market volatility. In particular, by reducing the reserved quantity of Bid A over time, processor  56  may reduce the risk of Trader A having exposure for a stale trading order  12  with a price that is no longer favorable for Trader A. 
     In some embodiments, trading platform  50  may comprise different decay rules  66  for different traders  70 . In particular, memory module  60  may store a respective trader profile  64  for each trader  70  in trading system  10 . Trader profile  64  for a particular trader  70  may comprise one or more decay rules  66  that are configurable by that trader  70 . In some embodiments, a particular trader profile  64  may comprise a first decay rule  66  for a first trading product, a second decay rule  66  for a second trading product, and so forth. Thus, a particular trader  70  may cause the reserved quantity of trading order  12  for a first trading product to decay at a different rate than the reserved quantity of trading order  12  for a second trading product. In some embodiments, upon receiving trading order  12 , processor  56  identifies the particular trader  70  that submitted trading order  12 . Processor  56  may then identify in memory module  60  trader profile  64  associated with the particular trader  70 . Processor  56  may then retrieve the appropriate decay rule  66  from the identified trader profile  64 . Thus, processor  56  may apply different decay rules  66  for different traders  70 . Processor  56  may update a decay rule  66  included in a trader profile  64  based on a decay rule  66  from a received trading order  12 . 
     Although decay rule(s)  66 , decay interval(s)  68 , and decay rate(s)  72  are shown in  FIG. 1  as being stored in the trading platform  50  in memory module  60 , any of decay rule(s)  66 , decay interval(s)  68 , and decay rate(s)  72 , etc., may be included in trading order  12 . Trading order  12  for a particular trading product may include, e.g., one or more decay rules  66  (and/or decay intervals, decay rates, decay quantities, etc.) associated with the particular trading product (or, e.g., any trading products that are related to the particular trading product). Trading order  12  originating from a particular trader may include, e.g., one or more decay rules  66  (and/or decay intervals, decay rates, decay quantities, etc.) associated with the particular trader (e.g., based on preferences of the particular trader). 
     In some embodiments, decay rule  66  may specify an initial decay interval  68  that is longer or shorter than successive decay intervals  68 . For example, a particular decay rule  66  may specify that, five minutes after trading platform  50  received trading order  12 , processor  56  begins decaying the reserved quantity of trading order  12 . After the initial five-minute interval, the particular decay rule  66  may specify that processor  56  continue to decay the reserved quantity after each successive minute. 
     Decay rule  66  may comprise any suitable formula, table, algorithm, and/or instructions for reducing the reserved quantity of trading order  12 . In some embodiments, decay rule  66  may comprise a formula for a variable decay rate  72 . For example, decay rule  66  may be a formula for an exponentially increasing decay rate  72 . 
       FIG. 3  is a table  300  that sets forth an example illustrating variable rate decay of trading order  12 , according to certain embodiments. In this example, decay rule  66  (e.g., stored in memory module  60  and/or specified by trading order  12  as described above) instructs processor  56  to decay the reserved quantity of trading order  12  at a rate of “10T′ where “T′ is the number of minutes since trading platform  50  received trading order  12 . At 11:42:12 a.m., trading platform  50  receives Bid A for one hundred units of Security Y. Bid A comprises a displayed quantity of ten units and a reserved quantity of ninety units. The trading product, displayed quantity, and reserved quantity associated with Bid A are illustrated in columns  302 ,  304 , and  306 , respectively. 
     In this example, processor  56  reduces the reserved quantity of Bid A according to decay rule  66 . In particular, at 11:43:12 a.m., processor  56  reduces the reserved quantity of Bid A by ten units (i.e., 10×1). At 11:44:12 a.m., processor  56  further reduces the reserved quantity of Bid A by twenty units (i.e., 10×2). With each successive minute, processor  56  reduces the reserved quantity of Bid A by an increasing amount according to decay rule  66 . The decay of the reserved quantity may continue until the reserved quantity is eliminated. Thus, decay rule  66  may specify a variable decay rate  72 . 
     Although the foregoing example illustrates decay rate  72  associated with a particular formula, it should be understood that decay rule  66  may comprise any suitable formula, table, algorithm, and/or instructions for reducing the reserved quantity of trading order  12  over time. 
     For example, in some embodiments, decay rule  66  is configured to cause the reserved quantity of trading order  12  to decay over time in response to one or more conditions. 
     Trading order  12  may specify decay rule  66  which may in turn specify the one or more conditions as well as, e.g., a decay interval, a decay rate, and/or a decay quantity, etc. 
     For example, for a trading order  12  for a particular trading product, a condition may relate to a market price of the particular trading product. For example, if the market price goes below (or, e.g., above) a certain value, then the reserved quantity (of the particular trading product) specified by trading order  12  should decay at, e.g., a particular decay rate  72  embedded in the trading order  12 . 
     The condition may relate to market activity external to the particular trading product of a trading order  12 . For example, the condition might involve a market index such as the Dow Jones Industrial Average. For example, if the Dow Jones Industrial Average goes below (or, e.g., above) a certain value, then the reserved quantity of trading order  12  should decay, e.g., according to a particular decay interval  68  and decay quantity specified by the trading order  12 . 
     The condition may relate to market activity external to, but more directly related to the particular trading product of a trading order  12 . For example, if the trading order concerns a bid/offer for the particular trading product in a cash market, the condition might involve a bid/offer for a derivative financial instrument based on the particular trading product in a futures market. For example, if the quantity available of the derivative financial instrument at a particular price of interest goes below (or, e.g., above) a certain value, then reserved quantity of trading order  12  should decay, e.g., according to the decay rule  66  specified by the trading order  12 . 
     The condition may relate to one or more products identified by, e.g., a process implemented by trading platform  50  (or by, e.g., a trader submitting the trading order  12 ) as being related (e.g., substantially equivalent) to a particular trading product of a trading order  12 . 
     For example, as described in more detail in U.S. patent application Ser. Nos. 11/399,019 and 11/399,112, both filed on Apr. 5, 2006, and each of which is hereby incorporated by reference herein in its entirety, trading platform  50  may be operable to identify relationships between trading products. Trading products may be related in a number of ways. For example, the historical performance of a ten-year note issued by entity X may be correlated to that of a five-year note issued by entity X. Although they are different trading products, the ten-year note and the five-year note share the same trading entity and are correlated in their performance trends. Thus, a trader who is interested in trading ten-year notes issued by entity X may also be interested in trading five-year notes issued by entity X. 
     The trading platform  50  may be operable to use current market data to determine a quantity of a particular trading product that may be equivalent to a quantity of a related trading product. For example, trading platform  50  may determine how may five-year notes are equivalent to a number of ten-year notes. Such a calculation may be based on any suitable number and combination of factors such as, for example, the coupons, frequencies, face values, prices, and maturity dates of five-year and ten-year notes. 
     The trading platform  50  may be operable to determine the liquidity associated with particular trading products. The liquidity associated with a trading product refers to the volume of trading product available for trading in market centers  40 . At any given time, the trading platform  50  may determine the available volume of a particular trading product in market centers  40 . 
     Using at least market data from, e.g., the market centers  40 , the trading platform  50  may generate a composite value. The composite value may be single value that encompasses the relationships among and the liquidity of multiple trading products in multiple market centers  40 . In particular, composite value may represent a quantity, size, or any other measurement of one or more related products that are available for trade in various market centers  40  at any given time. Composite value may be based on any suitable mathematical calculations and/or models for determining relationships among trading products. As an example, composite value may be configured to represent a quantity of “10-year equivalent” fixed income securities available for trade in market centers  40 . The quantity of 10-year equivalent securities may encompass the total number of available 10-year notes as well as a weighted quantity of 2-year notes, 3-year notes, 5-year notes, and/or any other suitable number and combination of related trading products. The weighted quantity of related trading products (e.g., 2-year notes, 3-year notes, 5-year notes, etc.) may be incorporated into composite value because that weighted quantity may be considered substantially equivalent (e.g., in performance, yield, price sensitivity to movements in a yield curve, and/or any other suitable number and combination of characteristics) to 10-year notes. 
     Conditions in decay rules  66  may involve, e.g., relationships between trading products, quantities between related trading products based on a determination that a quantity of a particular trading product may be equivalent to a quantity of a related trading product, liquidity of related trading products in market centers  40 , and composite value(s) determined for one or more related trading products. 
     For example, a condition in a decay rule  66  might involve a trading product that has been determined to be related to a particular trading product of trading order  12 . For example, if the quantity available of the related trading product at a particular price of interest goes below (or, e.g., above) a certain value, then reserved quantity of trading order  12  should decay, e.g., according to the decay rule  66  specified by the trading order  12 . 
     The condition may relate to activity external to the particular trading product of a trading order  12 . For example, the condition might involve a result of an event seemingly unrelated to the trading product of a trading order  12 , such as a result of a sporting event or an election. As an extreme example for illustrative purposes, the condition might involve a time during the trading day. For example, if the time of the day is, e.g., after 3 P.M., and the market is going to close for the day in, say, an hour, a particular decay rule  66  may be operative or, the time may trigger, e.g., a higher decay rate  72  than might be used at other times of the day. 
       FIG. 4  illustrates a flowchart for managing trading orders  12 , according to certain embodiments. The method begins at step  402  where trading platform  50  receives order  12   a  from client  20 . Order  12   a  may specify, e.g., decay rule  66  as described above. Decay rule  66  may specify decay interval  68  and/or decay rule  72 . Order  12   a  may be for a particular quantity of a trading product. A portion of the particular quantity of order  12   a  may be designated as a displayed quantity. The remaining portion of the particular quantity of order  12   a  may be designated as the reserved quantity. At step  404 , trading platform  50  discloses the displayed quantity of order  12   a  to market centers  40 . Disclosing the displayed quantity of order  12   a  may comprise transmitting data regarding the displayed quantity of order  12   a  to market centers  40 . 
     At step  406 , processor  56  determines whether trading platform  50  has received counterorder  12   b  that matches order  12   a . In some embodiments, the determination of whether counterorder  12   b  matches order  12   a  is based at least in part on whether counterorder  12   b  and order  12   a  are for the same product, the same price, and/or or crossing prices. If processor  56  determines at step  406  that trading platform  50  has not received counterorder  12   b  that matches order  12   a , then the method proceeds to step  414 . However, if processor  56  determines at step  406  that trading platform  50  has received counterorder  12   b  that matches order  12   a , then at step  408  processor  56  uses the counterorder  12   b  to fill the displayed quantity of order  12   a . At step  410 , processor  56  determines whether the reserved quantity of order  12   a  is greater than zero. If processor  56  determines at step  410  that the reserved quantity of order  12   a  is not greater than zero, then the method ends. However, if processor  56  determines at step  410  that the reserved quantity of order  12   a  is greater than zero, then at step  412  processor  56  uses a portion of the reserved quantity of order  12   a  to replenish the displayed quantity of order  12   a . The method then proceeds to step  414 . 
     At step  414 , processor  56  determines whether decay interval  68  associated with decay rule  66  (e.g., stored in memory module  60  and/or specified by trading order  12  as described above) has expired. If processor  56  determines at step  414  that decay interval  68  has not expired, then the method returns to step  406 . However, if processor  56  determines at step  414  that decay interval  68  has expired, then at step  416  processor  56  determines whether the reserved quantity of order  12   a  is greater than zero. If processor  56  determines at step  416  that the reserved quantity is not greater than zero, then the method returns to step  406 . However, if processor  56  determines at step  416  that the reserved quantity is greater than zero, then at step  418  processor  56  reduces the reserved quantity of order  12   a  by a configurable amount according to decay rule  66 . Decay rule  66  may comprise any suitable formula, table, algorithm, and/or instructions for reducing the reserved quantity of order  12   a  over time. Decay rule  66  may specify any suitable length of decay interval  68  and/or may specify any suitable decay rate  72 . After processor  56  reduces the reserved quantity of order  12   a  at step  418 , the method returns to step  406 . The method ends when, at step  410 , processor  56  determines that the reserved quantity of order  12   a  is not greater than zero. In some embodiments, the method may also end when order  12   a  expires and/or when trading platform  50  receives a cancel order associated with order  12   a.    
     Further Embodiments 
     The following should be interpreted as further embodiments and not as claims. 
     A1. A system, comprising:
         a memory operable to store a trading order for a particular quantity of a trading product, wherein:
           a first portion of the particular quantity is a displayed quantity; and   a second portion of the particular quantity is a reserved quantity;   
           a processor communicatively coupled to the memory and operable to:
           disclose the displayed quantity to one or more market centers;   identify a decay rate associated with the trading order; and   cause the reserved quantity to decay based at least in part on the identified decay rate.   
               

     A2. The system of A1, wherein:
         the trading order is received at a first time;   the decay rate is associated with a decay quantity and a time interval; and   causing the reserved quantity to decay based at least in part on the identified decay rate comprises:
           in response to expiration of the time interval after the first time, subtracting the decay quantity from the reserved quantity; and   in response to expiration of each successive time interval, subtracting the decay quantity from the reserved quantity such that the reserved quantity decays until the reserved quantity is eliminated.   
               

     A3. The system of A1, wherein:
         the decay rate is associated with a time interval; and   the decay rate is a variable rate such that, upon expiration of each successive time interval, the reserved quantity diminishes at an increasing rate.       

     A4. The system of A1, wherein:
         the decay rate is associated with a time interval; and   the decay rate is a variable rate such that, upon expiration of each successive time interval, the reserved quantity diminishes at a decreasing rate.       

     A5. The system of A1, wherein the processor is further operable to:
         receive a counterorder for the trading product;   fill the displayed quantity of the trading order with a portion of the counterorder; and   replenish the displayed quantity of the trading order with a portion of the reserved quantity of the trading order.       

     A6. The system of A5, wherein the displayed quantity of the trading order is replenished independently of the decay of the reserved quantity. 
     A7. The system of A1, wherein:
         the trading order is from a first trader;   the processor is further operable to receive a second trading order for the trading product;   the second trading order comprises a second displayed quantity and a second reserved quantity;   the second trading order is from a second trader; and   the processor is further operable to:
           identify a second decay rate associated with the second trader; and   cause the second reserved quantity to decay based at least in part on the second decay rate.   
               

     A8. The system of A1, wherein:
         the decay rate is a first decay rate, and the trading product is a first trading product; and   the memory is further operable to storing a plurality of decay rates, wherein each decay rate is associated with a respective trading product.       

     A9. The system of A1, wherein:
         the processor is further operable to record the displayed quantity and the reserved quantity in an order book; and   causing the reserved quantity to decay based at least in part on the identified decay rate comprises:
           in response to expiration of a first-time interval, deleting a first portion of the reserved quantity from the order book; and   in response to expiration of a second time interval, deleting a second portion of the reserved quantity from the order book.   
               

     B1. A method, comprising:
         receiving a trading order for a particular quantity of a trading product, wherein:
           a first portion of the particular quantity is a displayed quantity; and   a second portion of the particular quantity is a reserved quantity;   
           disclosing the displayed quantity to one or more market centers;   identifying a decay rate associated with the trading order; and   causing the reserved quantity to decay based at least in part on the identified decay rate.       

     B2. The method of B1, wherein:
         the trading order is received at a first time;   the decay rate is associated with a decay quantity and a time interval; and   causing the reserved quantity to decay based at least in part on the identified decay rate comprises:
           in response to expiration of the time interval after the first time, subtracting the decay quantity from the reserved quantity; and   in response to expiration of each successive time interval, subtracting the decay quantity from the reserved quantity such that the reserved quantity decays until the reserved quantity is eliminated.   
               

     B3. The method of B1, wherein:
         the decay rate is associated with a time interval; and   the decay rate is a variable rate such that, upon expiration of each successive time interval, the reserved quantity diminishes at an increasing rate.       

     B4. The method of B1, wherein:
         the decay rate is associated with a time interval; and   the decay rate is a variable rate such that, upon expiration of each successive time interval, the reserved quantity diminishes at a decreasing rate.       

     B5. The method of B1, further comprising:
         receiving a counterorder for the trading product;   filling the displayed quantity of the trading order with a portion of the counterorder; and   replenishing the displayed quantity of the trading order with a portion of the reserved quantity of the trading order.       

     B6. The method of B5, wherein the displayed quantity of the trading order is replenished independently of the decay of the reserved quantity. 
     B7. The method of B1, wherein:
         the trading order is from a first trader;   and further comprising:
           receiving a second trading order for the trading product, wherein:
               the second trading order comprises a second displayed quantity and a second reserved quantity; and   the second trading order is from a second trader;   
               identifying a second decay rate associated with the second trader; and   causing the second reserved quantity to decay based at least in part on the second decay rate.   
               

     B8. The method of B1, wherein:
         the decay rate is a first decay rate, and the trading product is a first trading product;   and further comprising:
           storing a plurality of decay rates, wherein each decay rate is associated with a respective trading product.   
               

     B9. The method of B1, further comprising:
         recording the displayed quantity and the reserved quantity in an order book;   wherein causing the reserved quantity to decay based at least in part on the identified decay rate comprises:
           in response to expiration of a first-time interval, deleting a first portion of the reserved quantity from the order book; and   in response to expiration of a second time interval, deleting a second portion of the reserved quantity from the order book.   
               

     C1. Logic encoded in computer-readable media and operable when executed by a processor to:
         receive a trading order for a particular quantity of a trading product, wherein:
           a first portion of the particular quantity is a displayed quantity; and   a second portion of the particular quantity is a reserved quantity;   
           disclose the displayed quantity to one or more market centers;   identify a decay rate associated with the trading order; and   cause the reserved quantity to decay based at least in part on the identified decay rate.       

     C2. The logic of C1, wherein:
         the trading order is received at a first time;   the decay rate is associated with a decay quantity and a time interval; and   causing the reserved quantity to decay based at least in part on the identified decay rate comprises:
           in response to expiration of the time interval after the first time, subtracting the decay quantity from the reserved quantity; and   in response to expiration of each successive time interval, subtracting the decay quantity from the reserved quantity such that the reserved quantity decays until the reserved quantity is eliminated.   
               

     D1. An apparatus, comprising:
         a processor; and   a memory, in which the memory is communicatively coupled to the processor, and in which the memory stores software instructions that, when executed by the processor, cause the processor to:
           receive, from a trader at a first time, a trading order for a particular quantity of a trading product, in which a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity, and in which the trading order specifies a decay rule;   identify the decay rule from the trading order, in which the decay rule is associated with at least one of the trader and the trading product, and in which the decay rule specifies at least a variable decay rate and a time interval;   disclose the displayed quantity of the trading order to one or more market centers;   receive a counterorder for another particular quantity of the trading product;   determine that the counterorder matches the trading order;   fill the displayed quantity of the trading order with at least a portion of the another particular quantity of the counterorder;   determine that the reserved quantity of the trading order is greater than zero;   replenish the displayed quantity of the trading order with a portion of the reserved quantity of the trading order, in which a remaining portion of the reserved quantity is left over after replenishing the displayed quantity;   determine that the time interval after the first time has expired;   after determining that the time interval after the first time has expired, determine that the remaining portion of the reserved quantity of the trading order is greater than zero;   reduce the remaining portion of the reserved quantity in accordance with the decay rule, in which any replenishing of the displayed quantity of the trading order occurs independently of reducing the remaining portion of the reserved quantity in accordance with the decay rule, and in which reducing the remaining portion of the reserved quantity in accordance with the decay rule comprises:
               after determining that the time interval after the first time has expired, reducing the remaining portion of the reserved quantity by a first quantity;   
               and   increase the variable decay rate; and   after an expiration of a successive time interval after the time interval, reduce the remaining portion of the reserved quantity by a second quantity, in which the second quantity is larger than the first quantity.   
               

     D2. The apparatus of D1, in which the software instructions, when executed by the processor, further cause the processor to:
         receive, from a second trader at a second time, a second trading order for still another particular quantity of the trading product, in which the still another particular quantity of the trading product comprises a second displayed quantity and a second reserved quantity, and in which the second trading order specifies a second decay rule; and   identify the second decay rule from the second trading order, in which the second decay rule is associated with at least the second trader and the trading product, and in which the second decay rule specifies at least a decay quantity.       

     D3. The apparatus of D2, in which the second decay rule further specifies at least a second time interval; and
         in which the software instructions, when executed by the processor, further cause the processor to:
           determine that the second time interval after the second time has expired;   in response to determining that the second time interval after the second time has expired, subtract the decay quantity from the second reserved quantity; and   for each second successive time interval until the second reserved quantity is zero, in response to an expiration of the second successive time interval, subtract the decay quantity from the second reserved quantity.   
               

     D4. The apparatus of D2, in which the software instructions, when executed by the processor, further cause the processor to:
         cause the second reserved quantity of the second trading order to decay based at least in part on the decay quantity.       

     D5. The apparatus of D1, in which the software instructions, when executed by the processor, further cause the processor to:
         upon receiving the trading order from the trader, identify the trader;   identify a trader profile associated with the trader; and   update another decay rule stored in the trader profile based at least in part on the decay rule from the trading order, in which the decay rule is associated with at least the trader.       

     D6. The apparatus of D1, in which the software instructions, when executed by the processor, further cause the processor to:
         receive, from a second trader, a second trading order for still another particular quantity of the trading product, in which the still another particular quantity of the trading product comprises a second displayed quantity and a second reserved quantity, and in which the second trading order specifies a second decay rule; and   identify the second decay rule from the second trading order, in which the second decay rule is associated with at least the second trader and the trading product, and in which the second decay rule specifies at least a second decay rate; and   cause the second reserved quantity of the second trading order to decay based at least in part on the second decay rate.       

     D7. The apparatus of D1, in which the variable decay rate is a first decay rate, and the trading product is a first trading product of a plurality of trading products; and 
     in which the software instructions, when executed by the processor, further cause the processor to:
         store a plurality of decay rates in the memory, in which each decay rate of the plurality of decay rates is associated with a respective trading product of the plurality of trading products.       

     D8. The apparatus of D1, in which the software instructions, when executed by the processor, further cause the processor to:
         record at least the reserved quantity of the trading order in an order book; and
 
in which reducing the remaining portion of the reserved quantity by the first quantity comprises:
   deleting the first quantity from the order book;
 
and in which reducing the remaining portion of the reserved quantity by the second quantity comprises:
   deleting the second quantity from the order book.       

     E1. A method, comprising:
         receiving, from a trader at a first time, by a processor of a computer, a trading order for a particular quantity of a trading product, in which a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity, and in which the trading order specifies a decay rule;   identifying, by the processor, the decay rule from the trading order, in which the decay rule is associated with at least one of the trader and the trading product, and in which the decay rule specifies at least a variable decay rate and a time interval;   disclosing, by the processor, the displayed quantity of the trading order to one or more market centers;   receiving, by the processor, a counterorder for another particular quantity of the trading product;   determining, by the processor, that the counterorder matches the trading order;   filling, by the processor, the displayed quantity of the trading order with at least a portion of another particular quantity of the counterorder;   determining, by the processor, that the reserved quantity of the trading order is greater than zero;   replenishing, by the processor, the displayed quantity of the trading order with a portion of the reserved quantity of the trading order, in which a remaining portion of the reserved quantity is left over after replenishing the displayed quantity;   determining, by the processor, that the time interval after the first time has expired;   after determining that the time interval after the first time has expired, determining, by the processor, that the remaining portion of the reserved quantity of the trading order is greater than zero;   reducing, by the processor, the remaining portion of the reserved quantity in accordance with the decay rule, in which any replenishing of the displayed quantity of the trading order occurs independently of reducing the remaining portion of the reserved quantity in accordance with the decay rule, and in which reducing the remaining portion of the reserved quantity in accordance with the decay rule comprises:
           after determining that the time interval after the first time has expired, reducing, by the processor, the remaining portion of the reserved quantity by a first quantity;   
           and   increasing, by the processor, the variable decay rate; and   after an expiration of a successive time interval after the time interval, reducing, by the processor, the remaining portion of the reserved quantity by a second quantity, in which the second quantity is larger than the first quantity.       

     E2. The method of E1, further comprising:
         receive, by the processor, from a second trader at a second time, a second trading order for still another particular quantity of the trading product, in which the still another particular quantity of the trading product comprises a second displayed quantity and a second reserved quantity, and in which the second trading order specifies a second decay rule; and   identifying, by the processor, the second decay rule from the second trading order, in which the second decay rule is associated with at least the second trader and the trading product, and in which the second decay rule specifies at least a decay quantity.       

     E3. The method of E2, in which the second decay rule further specifies at least a second time interval; and 
     in which the method further comprises:
         determining, by the processor, that the second time interval after the second time has expired;   in response to determining that the second time interval after the second time has expired, subtracting, by the processor, the decay quantity from the second reserved quantity; and   for each second successive time interval until the second reserved quantity is zero, in response to an expiration of the second successive time interval, subtracting, by the processor. the decay quantity from the second reserved quantity.       

     E4. The method of E2, further comprising:
         causing, by the processor, the second reserved quantity of the second trading order to decay based at least in part on the decay quantity.       

     E5. The method of E1, further comprising:
         upon receiving the trading order from the trader, identifying, by the processor, the trader;   identifying, by the processor, a trader profile associated with the trader; and   updating, by the processor, another decay rule stored in the trader profile based at least in part on the decay rule from the trading order, in which the decay rule is associated with at least the trader.       

     E6. The method of E1, further comprising:
         receiving, by the processor, from a second trader, a second trading order for still another particular quantity of the trading product, in which the still another particular quantity of the trading product comprises a second displayed quantity and a second reserved quantity, and in which the second trading order specifies a second decay rule;   identifying, by the processor, the second decay rule from the second trading order, in which the second decay rule is associated with at least the second trader and the trading product, and in which the second decay rule specifies at least a second decay rate; and   causing, by the processor, the second reserved quantity of the trading order to decay based at least in part on the second decay rate.       

     E7. The method of E1, in which the variable decay rate is a first decay rate, and the trading product is a first trading product of a plurality of trading products; and in which the method further comprises:
         storing, by the processor, a plurality of decay rates, in which each decay rate of the plurality of decay rates is associated with a respective trading product of the plurality of trading products.       

     E8. The method of E1, further comprising:
         recording, by the processor, at least the reserved quantity of the trading order in an order book;
 
and
 
in which reducing the remaining portion of the reserved quantity by the first quantity comprises:
   deleting, by the processor, the first quantity from the order book; and   deleting, by the processor, the second quantity from the order book.       

     F1. A computer-readable medium, the computer-readable medium being a tangible medium, the computer-readable medium storing software instructions that, when executed by a processor, cause the processor to:
         receive, from a trader at a first time, a trading order for a particular quantity of a trading product, in which a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity, and in which the trading order specifies a decay rule;   identify the decay rule from the trading order, in which the decay rule is associated with at least one of the trader and the trading product, and in which the decay rule specifies at least a variable decay rate and a time interval;   disclose the displayed quantity of the trading order to one or more market centers;   receive a counterorder for another particular quantity of the trading product;   determine that the counterorder matches the trading order;   fill the displayed quantity of the trading order with at least a portion of the another particular quantity of the counterorder;   determine that the reserved quantity of the trading order is greater than zero;   replenish the displayed quantity of the trading order with a portion of the reserved quantity of the trading order, in which a remaining portion of the reserved quantity is left over after replenishing the displayed quantity;   determine that the time interval after the first time has expired;   after determining that the time interval after the first time has expired, determine that the remaining portion of the reserved quantity of the trading order is greater than zero;   reduce the remaining portion of the reserved quantity in accordance with the decay rule, in which any replenishing of the displayed quantity of the trading order occurs independently of reducing the remaining portion of the reserved quantity in accordance with the decay rule, and in which reducing the remaining portion of the reserved quantity in accordance with the decay rule comprises:
           after determining that the time interval after the first time has expired, reducing the remaining portion of the reserved quantity by a first quantity;   
           and   increase the variable decay rate; and   after an expiration of a successive time interval after the time interval, reduce the remaining portion of the reserved quantity by a second quantity, in which the second quantity is larger than the first quantity.       

     F2. The computer-readable medium of F1, in which the software instructions, when executed by the processor, further cause the processor to:
         receive, from a second trader at a second time, a second trading order for still another particular quantity of the trading product, in which the still another particular quantity of the trading product comprises a second displayed quantity and a second reserved quantity, and in which the second trading order specifies a second decay rule; and   identify the second decay rule from the second trading order, in which the second decay rule is associated with at least the second trader and the trading product, and in which the second decay rule specifies at least a decay quantity.       

     F3. The computer-readable medium of F2, in which the second decay rule further specifies at least a second time interval; and 
     in which the software instructions, when executed by the processor, further cause the processor to:
         determine that the second time interval after the second time has expired;   in response to determining that the second time interval after the second time has expired, subtract the decay quantity from the second reserved quantity; and   for each second successive time interval until the second reserved quantity is zero, in response to an expiration of the second successive time interval, subtract the decay quantity from the second reserved quantity.
 
F4. The computer-readable medium of F2, in which the software instructions, when executed by the processor, further cause the processor to:
   cause the second reserved quantity of the second trading order to decay based at least in part on the decay quantity.       

     F5. The computer-readable medium of F1, in which the software instructions, when executed by the processor, further cause the processor to:
         upon receiving the trading order from the trader, identify the trader;   identify a trader profile associated with the trader; and   update another decay rule stored in the trader profile based at least in part on the decay rule from the trading order, in which the decay rule is associated with at least the trader.       

     F6. The computer-readable medium of F1, in which the software instructions, when executed by the processor, further cause the processor to:
         receive, from a second trader, a second trading order for still another particular quantity of the trading product, in which the still another particular quantity of the trading product comprises a second displayed quantity and a second reserved quantity, and in which the second trading order specifies a second decay rule; and   identify the second decay rule from the second trading order, in which the second decay rule is associated with at least the second trader and the trading product, and in which the second decay rule specifies at least a second decay rate; and   cause the second reserved quantity of the second trading order to decay based at least in part on the second decay rate.       

     F7. The computer-readable medium of F1, in which the variable decay rate is a first decay rate, and the trading product is a first trading product of a plurality of trading products; and 
     in which the software instructions, when executed by the processor, further cause the processor to:
         store a plurality of decay rates in a memory, in which each decay rate of the plurality of decay rates is associated with a respective trading product of the plurality of trading products.       

     F8. The computer-readable medium of F1, in which the software instructions, when executed by the processor, further cause the processor to:
         record at least the reserved quantity of the trading order in an order book;
 
and
 
in which reducing the remaining portion of the reserved quantity by the first quantity comprises:
   deleting the first quantity from the order book;
 
and in which reducing the remaining portion of the reserved quantity by the second quantity comprises:
   deleting the second quantity from the order book.       

     G1. An apparatus, comprising:
         a processor; and   a memory, in which the memory is communicatively coupled to the processor, and in which the memory stores software instructions that, when executed by the processor, cause the processor to:
           receive, from a trader at a first time, a trading order for a particular quantity of a trading product, in which a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity, and in which the trading order specifies a decay rule;   identify the decay rule from the trading order, in which the decay rule is associated with at least one of the trader and the trading product, and in which the decay rule specifies at least a variable decay rate and a time interval;   disclose the displayed quantity of the trading order to one or more market centers;   determine that the time interval after the first time has expired;   after determining that the time interval after the first time has expired, determine that the reserved quantity of the trading order is greater than zero; and   reduce the reserved quantity in accordance with the variable decay rate without changing the displayed quantity of the trading order, in which reducing the reserved quantity in accordance with the variable decay rate comprises;
               after determining that the time interval after the first time has expired, reducing the reserved quantity by a first quantity;   
               and   increase the variable decay rate; and   after an expiration of a successive time interval after the time interval, reduce the reserved quantity by a second quantity, in which the second quantity is larger than the first quantity.   
               

     H1. A method, comprising:
         receiving, from a trader at a first time, by a processor of a computer, a trading order for a particular quantity of a trading product, in which a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity, and in which the trading order specifies a decay rule;   identifying, by the processor, the decay rule from the trading order, in which the decay rule is associated with at least one of the trader and the trading product, and in which the decay rule specifies at least a variable decay rate and a time interval;   disclosing, by the processor, the displayed quantity of the trading order to one or more market centers;   determining, by the processor, that the time interval after the first time has expired;   after determining that the time interval after the first time has expired, determining, by the processor, that the reserved quantity of the trading order is greater than zero; and   reducing, by the processor, the reserved quantity in accordance with the variable decay rate without changing the displayed quantity of the trading order, in which reducing the reserved quantity in accordance with the variable decay rate comprises;
           after determining that the time interval after the first time has expired, reducing, by the processor, the reserved quantity by a first quantity;   
           and   increasing, by the processor, the variable decay rate; and   after an expiration of a successive time interval after the time interval, reducing, by the processor, the reserved quantity by a second quantity, in which the second quantity is larger than the first quantity.       

     I1. A computer-readable medium, the computer-readable medium being a tangible medium, the computer-readable medium storing software instructions that, when executed by a processor, cause the processor to:
         receive, from a trader at a first time, a trading order for a particular quantity of a trading product, in which a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity, and in which the trading order specifies a decay rule;   identify the decay rule from the trading order, in which the decay rule is associated with at least one of the trader and the trading product, and in which the decay rule specifies at least a variable decay rate and a time interval;   disclose the displayed quantity of the trading order to one or more market centers;   determine that the time interval after the first time has expired;   after determining that the time interval after the first time has expired, determine that the reserved quantity of the trading order is greater than zero; and   reduce the reserved quantity in accordance with the variable decay rate without changing the displayed quantity of the trading order, in which reducing the reserved quantity in accordance with the variable decay rate comprises;
           after determining that the time interval after the first time has expired, reducing the reserved quantity by a first quantity;   
           and   increase the variable decay rate; and   after an expiration of a successive time interval after the time interval, reduce the reserved quantity by a second quantity, in which the second quantity is larger than the first quantity.       

     J1. An apparatus, comprising:
         a processor; and   a memory, in which the memory is communicatively coupled to the processor, and in which the memory stores software instructions that, when executed by the processor, cause the processor to:
           receive, from a trader at a first time, a trading order for a particular quantity of a trading product, in which a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity, and in which the trading order specifies a decay rule;   identify the decay rule from the trading order, in which the decay rule is associated with at least one of the trader and the trading product, and in which the decay rule specifies at least a variable decay rate and a time interval;   disclose the displayed quantity of the trading order to one or more market centers;   receive a counterorder for another particular quantity of the trading product;   determine that the counterorder matches the trading order;   fill the displayed quantity of the trading order with at least a portion of another particular quantity of the counterorder;   determine that the reserved quantity of the trading order is greater than zero;   replenish the displayed quantity of the trading order with a portion of the reserved quantity of the trading order, in which a remaining portion of the reserved quantity is left over after replenishing the displayed quantity;   determine that the time interval after the first time has expired;   after determining that the time interval after the first time has expired, determine that the remaining portion of the reserved quantity of the trading order is greater than zero;   reduce the remaining portion of the reserved quantity in accordance with the decay rule, in which any replenishing of the displayed quantity of the trading order occurs independently of reducing the remaining portion of the reserved quantity in accordance with the decay rule, and in which reducing the remaining portion of the reserved quantity in accordance with the decay rule comprises:
               after determining that the time interval after the first time has expired, reducing the remaining portion of the reserved quantity by a first quantity;   
               and   decreasing the variable decay rate; and   after an expiration of a successive time interval after the time interval, reduce the remaining portion of the reserved quantity by a second quantity, in which the second quantity is smaller than the first quantity.   
               

     K1. A method, comprising:
         receiving, from a trader at a first time, by a processor of a computer, a trading order for a particular quantity of a trading product, in which a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity, and in which the trading order specifies a decay rule;   identifying, by the processor, the decay rule from the trading order, in which the decay rule is associated with at least one of the trader and the trading product, and in which the decay rule specifies at least a variable decay rate and a time interval;   disclosing, by the processor, the displayed quantity of the trading order to one or more market centers;   receiving, by the processor, a counterorder for another particular quantity of the trading product;   determining, by the processor, that the counterorder matches the trading order;   filling, by the processor, the displayed quantity of the trading order with at least a portion of another particular quantity of the counterorder;   determining, by the processor, that the reserved quantity of the trading order is greater than zero;   replenishing, by the processor, the displayed quantity of the trading order with a portion of the reserved quantity of the trading order, in which a remaining portion of the reserved quantity is left over after replenishing the displayed quantity;   determining, by the processor, that the time interval after the first time has expired;   after determining that the time interval after the first time has expired, determining, by the processor, that the remaining portion of the reserved quantity of the trading order is greater than zero;   reducing, by the processor, the remaining portion of the reserved quantity in accordance with the decay rule, in which any replenishing of the displayed quantity of the trading order occurs independently of reducing the remaining portion of the reserved quantity in accordance with the decay rule, and in which reducing the remaining portion of the reserved quantity in accordance with the decay rule comprises:
           after determining that the time interval after the first time has expired, reducing, by the processor, the remaining portion of the reserved quantity by a first quantity;   
           and   decreasing, by the processor, the variable decay rate; and   after expiration of a successive time interval after the time interval, reducing, by the processor, the remaining portion of the reserved quantity by a second quantity, in which the second quantity is smaller than the first quantity.       

     L1. A computer-readable medium, the computer-readable medium being a tangible medium, the computer-readable medium storing software instructions that, when executed by a processor, cause the processor to:
         receive, from a trader at a first time, a trading order for a particular quantity of a trading product, in which a first portion of the particular quantity is a displayed quantity, and a second portion of the particular quantity is a reserved quantity, and in which the trading order specifies a decay rule;   identify the decay rule from the trading order, in which the decay rule is associated with at least one of the trader and the trading product, and in which the decay rule specifies at least a variable decay rate and a time interval;   disclose the displayed quantity of the trading order to one or more market centers;   receive a counterorder for another particular quantity of the trading product;   determine that the counterorder matches the trading order;   fill the displayed quantity of the trading order with at least a portion of another particular quantity of the counterorder;   determine that the reserved quantity of the trading order is greater than zero;   replenish the displayed quantity of the trading order with a portion of the reserved quantity of the trading order, in which a remaining portion of the reserved quantity is left over after replenishing the displayed quantity;   determine that the time interval after the first time has expired;   after determining that the time interval after the first time has expired, determine that the remaining portion of the reserved quantity of the trading order is greater than zero;   reduce the remaining portion of the reserved quantity in accordance with the decay rule, in which any replenishing of the displayed quantity of the trading order occurs independently of reducing the remaining portion of the reserved quantity in accordance with the decay rule, and in which reducing the remaining portion of the reserved quantity in accordance with the decay rule comprises:
           after determining that the time interval after the first time has expired, reducing the remaining portion of the reserved quantity by a first quantity;   
           and   decrease the variable decay rate; and   after an expiration of a successive time interval after the time interval, reduce the remaining portion of the reserved quantity by a second quantity, in which the second quantity is smaller than the first quantity.       

     Although the present invention has been described in several embodiments, a myriad of changes and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes and modifications as fall within the scope of the present appended claims.