Stock Performance Graph The following graph compares the most recent five-year performance of Alcoa’s common stock with (1) the Standard & Poor’s 500?
Index and (2) the Standard & Poor’s 500?
Materials Index, a group of 27 companies categorized by Standard & Poor’s as active in the “materials” market sector.
Such information shall not be deemed to be “filed.
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## Table 0 ##
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## Table 1 ##
3.
FAIR VALUE OFASSETS AND LIABILITIES The carrying value and fair value of financial instruments is presented in the below summary table.
The fair value of financial instruments held by consolidated investment products is presented in Note 20, "Consolidated Investment Products. "
## Table 2 ##
* These financial instruments are not measured at fair value on a recurring basis.
See the indicated footnotes for additional information about the carrying and fair values of these financial instruments.
Foreign time deposits are measured at cost plus accrued interest, which approximates fair value.
A three-level valuation hierarchy exists for disclosure of fair value measurements based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date.
The three levels are defined as follows: ?
Level 1 - inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities in active markets.  ?
Level 2 - inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument.  ?
Level 3 - inputs to the valuation methodology are unobservable and significant to the fair value measurement.
An asset or liability's categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.
There are three types of valuation approaches: a market approach, which uses observable prices and other relevant information that is generated by market transactions involving identical or comparable assets or liabilities; an income approach, which uses valuation techniques to convert future amounts to a single, discounted present value amount; and a cost approach, which is based on the amount that currently would be required to replace the service capacity of an asset.
The following is a description of the valuation methodologies used for assets and liabilities measured at fair value on a recurring
Table of Contents Contractual Obligations We have various financial obligations that require future cash payments.
The following table outlines the timing of payment requirements related to our commitments as of December 31, 2011:
## Table 3 ##
(1) Total debt includes $745.7 million of fixed rate debt.
Fixed interest payments are therefore reflected in the table above in the periods they are due.
The credit facility, $539.0 million outstanding at December 31, 2011, provides for borrowings of various maturities.
Interest is payable based upon LIBOR, Prime, Federal Funds or other bank-provided rates in existence at the time of each borrowing.
(2) Operating leases reflect obligations for leased building space.
See Item 8, Financial Statements and Supplementary Data - Note 14, “Operating Leases” for sublease information.
(3) Expected future contributions to defined benefit plans of $43.8 million are estimated for the next five years, and are comprised of $31.8 million related to pension plans and $12.0 million related to a postretirement medical plan.
See Item 8, Financial Statements and Supplementary Data - Note 13, “Retirement Benefit Plans” for detailed benefit pension and postretirement plan information.
(4) The company has capital commitments into co-invested funds that are to be drawn down over the life of the partnership as investment opportunities are identified.
At December 31, 2011, the company's undrawn capital commitments were $161.2 million.
See Note 19, “Commitments and Contingencies” for additional details.
(5) Due to the uncertainty with respect to the timing of future cash flows associated with unrecognized tax benefits at December 31, 2011, the company is unable to make reasonably reliable estimates of the period of cash settlement with the respective taxing authorities.
Therefore, $19.5 million of gross unrecognized tax benefits have been excluded from the contractual obligations table above.
See Item 8, Financial Statements and Supplementary Data, Note 16 - “Taxation” for a discussion on income taxes.
Critical Accounting Policies and Estimates Our significant accounting policies are disclosed in Item 8, Financial Statements and Supplementary Data - Note 1, “Accounting Policies” to our Consolidated Financial Statements.
The accounting policies and estimates that we believe are the most critical to an understanding of our results of operations and financial condition are those that require complex management judgment regarding matters that are highly uncertain at the time policies were applied and estimates were made.
These accounting policies and estimates are discussed below; however, the additional accounting policy detail in the footnote previously referenced is important to the discussion of each of the topics.
Different estimates reasonably could have been used in the current period that would have had a material effect on these financial statements, and changes in these estimates are likely to occur from period-to-period in the future.
Taxation.
We operate in several countries and several states through our various subsidiaries, and must allocate our income, expenses, and earnings under the various laws and regulations of each of these taxing jurisdictions.
Accordingly, our provision for income taxes represents our total estimate of the liability that we have incurred for doing business each year in all of our locations.
Annually we file tax returns that represent our filing positions within each jurisdiction and settle our return liabilities.
Each jurisdiction has the right to audit those returns and may take different positions with respect to income and expense allocations and taxable earnings determinations.
Because the determinations of our annual provisions are subject to judgments and estimates, it is possible that actual results will vary from those recognized in our financial statements.
As a result, it is likely that additions to, or reductions of, income tax expense will occur each year for prior reporting periods as actual tax returns and tax audits are settled.
the nature of the business; making a significant accounting policyy change in certain situations; entering into transactions with affiliates; and incurring indebtedness through the subsidiaries (other than the borrower, Invesco Finance PLC).
Many of these restrictions are subject to certain minimum thresholds and exceptions.
Financial covenants under the credit agreement include: (i) the quarterly maintenance of a debt/EBITDA leverage ratio, as defined in the credit agreement, of not greater than 3.25:1.00, (ii) a coverage ratio (EBITDA, as defined in the credit agreement/interest payable for the four consecutive fiscal quarters ended before the date of determination) of not less than 4.00:1.00.
The credit agreement governing the credit facility also contains customary provisions regarding events of default which could result in an acceleration or increase in amounts due, including (subject to certain materiality thresholds and grace periods) payment default, failure to comply with covenants, material inaccuracy of representation or warranty, bankruptcy or insolvency proceedings, change of control, certain judgments, ERISA matters, cross-default to other debt agreements, governmental action prohibiting or restricting the company or its subsidiaries in a manner that has a material adverse effect and failure of certain guaranty obligations.
The company is in compliance with all regulatory minimum net capital requirements.
The lenders (and their respective affiliates) may have provided, and may in the future provide, investment banking, cash management, underwriting, lending, commercial banking, leasing, foreign exchange, trust or other advisory services to the company a and its subsidiaries and affiliates.
These parties may have received, and may in the future receive, customary compensation forrthese services.
At December 31, 2017, the company maintains approximately $10.6 million in letters of credit from a variety of banks.
The letters of credit are generally one-year automatically-renewable facilities and are maintained for various commercial reasons.9.
SHARE CAPITAL The number of common shares and common share equivalents issued are represented in the table below:
## Table 4 ##
The company did not purchase shares in the open market during the twelve months ended December 31, 2017 (year ended December 31, 2016: 18.1 million shares at a cost of $535.0 million).
Separately, an aggregate of 1.9 million shares were withheld on vesting events during the year ended December 31, 2017 to meet employees' withholding tax obligations (December 31, 2016: 1.5 million).
The fair value of these shares withheld at the respective withholding dates was $63.8 million (December 31, 2016: $42.0 million).
At December 31, 2017, approximately $1,643.0 million remained authorized under the company's share repurchase authorizations approved by the Board on October 11, 2013 and July 22, 2016 (December 31, 2016: $1,643.0 million).
Total treasury shares at December 31, 2017 were 92.4 million (December 31, 2016: 95.9 million), including 9.1 million unvested restricted stock awards (December 31, 2016: 9.3 million) for which dividend and voting rights apply.
The market price of common shares at the end of 2017 was $36.54.
The total market value of the company's 92.4 million treasury shares was $3.4 billion at December 31, 2017.
Movements in Treasury Shares comprise:

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As of December 31,	2010	2011	2012	2013	2014	2015
AlcoaInc.	$100	$57	$58	$72	$107	$68
S&P 500®Index	100	102	118	157	178	181
S&P 500®Materials Index	100	90	104	130	139	128

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For the year ended December 31,
$ in millions	2011	2010
Acquisition-related charges	—	5.7
Integration-related charges:
Staff costs	2.8	39.1
Technology, contractor and related costs	11.0	53.4
Professional services	15.6	51.8
Total integration-related charges	29.4	144.3
Total transaction and integration charges	29.4	150.0

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December 31, 2011	December 31, 2010
$ in millions	Footnote Reference	Carrying Value	Fair Value	Carrying Value	Fair Value
Cash and cash equivalents	727.4	727.4	740.5	740.5
Available for sale investments	4	63.5	63.5	100.0	100.0
Assets held for policyholders	1,243.5	1,243.5	1,295.4	1,295.4
Trading investments	4	187.5	187.5	180.6	180.6
Foreign time deposits*	4	32.2	32.2	28.2	28.2
Support agreements*	19,20	-1.0	-1.0	-2.0	-2.0
Policyholder payables	-1,243.5	-1,243.5	-1,295.4	-1,295.4
Financial instruments sold, not yet purchased	-1.0	-1.0	-0.7	-0.7
Derivative liabilities	—	—	-0.1	-0.1
Note Payable	-16.8	-16.8	-18.9	-18.9
Total debt*	9	-1,284.7	-1,307.5	-1,315.7	-1,339.3

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$ in millions	Total-4(5)	Within 1 Year	1-3 Years	3-5 Years	More Than 5 Years
Total debt	1,284.7	215.1	530.6	539.0	—
Estimated interest payments on total debt-1	90.6	40.1	39.2	11.3	—
Operating leases-2	618.0	69.4	133.1	127.0	288.5
Defined benefit pension and postretirement medical obligations-3	43.8	8.3	26.3	9.2	N/A
Total	2,037.1	332.9	729.2	686.5	288.5

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In millions	December 31, 2017	December 31, 2016	December 31, 2015
Common shares issued	490.4	490.4	490.4
Less: Treasury shares for which dividend and voting rights do not apply	-83.3	-86.6	-72.9
Common shares outstanding	407.1	403.8	417.5

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Question: Which year is Cash and cash equivalents the most?
Answer: 2011