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**UNITED      STATES**

**SECURITIES      AND EXCHANGE COMMISSION**

**Washington,      D.C. 20549**

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**FORM**
**        10-Q/A**

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| **þ** | **QUARTERLY                  REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE                  ACT OF                  1934** |
|------------|------------------------------------------------------------------------------------------------------------------------------------------------|

**For      the quarterly period ended March 31, 2008**

| **o** | **TRANSITION                  REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE                  ACT OF                  1934** |
|-------|-------------------------------------------------------------------------------------------------------------------------------------------------|

**For      the transition period from    **
**to    **

**Commission      file number: 001-02292**

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**NYFIX,      INC.**

**(Exact      name of registrant as specified in its charter)**

| **Delaware****(State                or other jurisdiction of****incorporation                or organization)**                          | **06-1344888****(I.R.S.                Employer****Identification                Number)** |
|------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------|
|  **100                Wall Street****New                York, New York****(Address                of principal executive offices)** |  **10005****(Zip                code)**                                               |

**(646)      525-3000**

**(Registrant’s      telephone number, including area code) **

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**x      **

| Large accelerated Filer  ̈ | Accelerated                filer ý | Non-accelerated                filer  ̈ | Smaller reporting company  ̈ |
|-----------------------------------------------|-----------------------------------------|---------------------------------------------|-------------------------------------------------|

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**EXPLANATORY        NOTE**

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**Signatures**

|                      |  NYFIX, INC.                                                 |
|---------------------------|------------------------------------------------------------------------|
|                      |                                                                   |
| August 20, 2008 | /s/ P.                Howard Edelstein                  |
|                      | P.                Howard Edelstein                                |
|                      | President                and Chief Executive Officer    |
|                      |                                                                   |
| August 20, 2008 | /s/ Steven                R. Vigliotti                       |
|                      | Steven                R. Vigliotti                           |
|                      | Chief                Financial Officer                            |

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**Item        6. Exhibits**

| **Exhibit****No. ** | **Description                of                Exhibit** |
|--------------------------|----------------------------------------------------------|
|   |   |
|--------|--------|
| *                 10.1 † | Agreement                  for the Sale and Purchase of the entire issued share capital of                  FIXCITY, LTD dated April 4, 2008 |
|-------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------|
|   |   |
|--------|--------|
| 10.2 (1) | NYFIX, Inc. 2008 Annual Incentive                Plan |
|----------|-------------------------------------------------------|
|   |   |
|--------|--------|
| * 31.3 | Certification of Chief Executive                Officer                pursuant to Rules 13a-14(a) or 15d-14(a) of the Securities Exchange                Act of                1934, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act                of                2002. |
|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |   |
|--------|--------|
| * 31.4 | Certification of Chief Financial                Officer                pursuant to Rules 13a-14(a) or 15d-14(a) of the Securities Exchange                Act of                1934, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act                of                2002. |
|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| * | Filed                  herewith |
|---|---------------------------------|

| † | Confidential                  treatment requested as to certain portions, which portions are                  omitted and                  filed separately with the Securities and Exchange                  Commission. |
|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (1) | Previously                  filed on May 12, 2008. |
|-----|----------------------------------------------------|

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