B. Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation

These condensed consolidated financial statements are unaudited and, in the opinion of management, include all adjustments necessary for a fair statement of the financial position and results of operations of the Company for the interim periods presented. Such adjustments consisted only of normal recurring items. The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America.

In accordance with accounting principles generally accepted in the United States of America for interim financial reports and the instructions for Form 10-Q and the rules of the Securities and Exchange Commission, certain information and footnote disclosures normally included in annual financial statements have been condensed or omitted. Our accounting policies are described in the Notes to the Financial Statements in our Annual Report on Form 10-K for the year ended December 31, 2012. Interim results are not necessarily indicative of the results of operations for the full year. These interim financial statements should be read in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2012.

Use of Estimates and Assumptions

The preparation of condensed consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the related disclosure of contingent assets and liabilities. The most significant estimates and assumptions are used in, but are not limited to, revenue recognition related to product sales and collaboration agreements, product sales allowances and accruals, assessing investments for potential other-than-temporary impairment and determining values of investments, estimates used to measure the fair value of our assets held for sale, accrued expenses, income taxes and equity-based compensation expense. Actual results could differ materially from those estimates.

Principles of Consolidation

The accompanying condensed consolidated financial statements include our accounts and the accounts of our wholly-owned subsidiaries, AMAG Europe Limited and AMAG Securities Corporation. AMAG Europe Limited was incorporated in October 2009 in London, England. AMAG Securities Corporation is a Massachusetts corporation which was incorporated in August 2007. All intercompany account balances and transactions between the companies have been eliminated.

Fair Value of Financial Instruments

Under current accounting standards, fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs.

Current accounting guidance establishes a hierarchy used to categorize how fair value is measured and which is based on three levels of inputs, of which the first two are considered observable and the third unobservable, as follows:

Level 1 - Quoted prices in active markets for identical assets or liabilities.

Level 2 - Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Assets Measured at Fair Value on a Recurring Basis

We hold certain assets that are required to be measured at fair value on a recurring basis, including our cash equivalents and investments. The following tables represent the fair value hierarchy as of March 31, 2013 and December 31, 2012 for those assets that we measure at fair value on a recurring basis (in thousands):

	Fair Value Measurements at March 31, 2013 Using:
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		(Level 1)		(Level 2)		(Level 3)
Money market funds	$	21,542	$	21,542	$	—	$	—
Corporate debt securities	124,710		—		124,710		—
U.S. treasury and government agency securities	54,517		—		54,517		—
Commercial paper	3,997		—		3,997		—
	$	204,766	$	21,542	$	183,224	$	—

	Fair Value Measurements at December 31, 2012 Using:
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		(Level 1)		(Level 2)		(Level 3)
Money market funds	$	24,058	$	24,058	$	—	$	—
Corporate debt securities	111,690		—		111,690		—
U.S. treasury and government agency securities	59,569		—		59,569		—
Commercial paper	9,491		—		9,491		—
	$	204,808	$	24,058	$	180,750	$	—

With the exception of our money market funds, the fair value of our investments is primarily determined from independent pricing services which use Level 2 inputs to determine fair value. Independent pricing services normally derive security prices from recently reported trades for identical or similar securities, making adjustments based upon other significant observable market transactions. At the end of each reporting period, we perform quantitative and qualitative analyses of prices received from third parties to determine whether prices are reasonable estimates of fair value. After completing our analyses, we did not adjust or override any fair value measurements provided by our pricing services as of either March 31, 2013 or December 31, 2012. In addition, there were no transfers or reclassifications of any securities between Level 1 and Level 2 during the three months ended March 31, 2013.

Assets Held for Sale

During 2012, we determined that certain assets related to our Cambridge, Massachusetts manufacturing facility, including the related land, building and certain equipment, met the criteria established by current accounting guidance for classifying assets as held for sale. As a result, during 2012, we reclassified these assets from property and equipment to assets held for sale in our condensed consolidated balance sheet. In anticipation of a future sale, we valued these assets at the lower of their carrying amount or fair value less cost to sell to arrive at the estimated fair value of $2.0 million as of December 31, 2012. During the three months ended March 31, 2013, we sold $0.4 million of equipment related to our Cambridge, Massachusetts manufacturing facility. In connection with these sales, we recorded a gain of $0.3 million and reduced the carrying value of our assets held for sale by $0.1 million to $1.9 million. The fair values of the land, building, and equipment were estimated using Level 3 inputs, which included offers received from potential purchasers, real estate appraisals and other estimates from third-parties.

Revenue Recognition and Related Sales Allowances and Accruals

We recognize revenue from the sale of Feraheme/Rienso as well as license fee and other collaboration revenues, including milestone payments, other product sale revenues, and royalties we receive from our licensees. We recognize revenue in accordance with current accounting guidance related to the recognition, presentation and disclosure of revenue in financial statements, which outlines the basic criteria that must be met to recognize revenue and provides guidance for disclosure of revenue in financial statements.

We record product sales allowances and accruals related to prompt payment discounts, chargebacks, government and other rebates, distributor, wholesaler and group purchasing organization, or GPO, fees, and product returns as a reduction of revenue in our condensed consolidated statement of operations at the time product sales are recorded. Calculating these gross-to-net sales adjustments involves estimates and judgments based primarily on actual Feraheme sales data, forecasted customer buying patterns, and market research data related to utilization rates by various end-users. In addition, we also monitor our distribution channel to determine whether additional allowances or accruals are required based on inventory in our sales channel.

An analysis of our product sales allowances and accruals for the three months ended March 31, 2013 and 2012 is as follows (in thousands):

	Three Months Ended March 31,
	2013			2012
Provision for U.S. product sales allowances and accruals
Discounts and chargebacks	$	7,493		$	5,892
Government and other rebates	2,387			1,460
Returns	193			(266		)
Total provision for U.S. product sales allowances and accruals	$	10,073		$	7,086

Total gross U.S. product sales	$	25,651		$	20,712

Total provision for U.S. product sales allowances and accruals as a percent of total gross U.S. product sales	39		%	34		%

We generally offer our wholesalers, specialty distributors and other customers a limited right to return product purchased directly from us, principally based on the product’s expiration date which, once packaged, is currently five years in the U.S. Reserves for product returns for U.S. sales are recorded in the period the related revenue is recognized, resulting in a reduction to product sales. We evaluate our estimated product returns rate each period based on the historical return patterns and known or expected changes in the marketplace. We did not significantly adjust our reserve for product returns during the three months ended March 31, 2013. During the three months ended March 31, 2012, we reduced our reserve by approximately $0.5 million of previously reserved product returns allowance due to the lapse of the product return period on certain manufactured Feraheme lots that carried a two year expiration period. The product returns provision applied to gross product sales for the three months ended March 31, 2013 was $0.2 million as compared to a credit of $0.3 million in the three months ended March 31, 2012.

Concentrations and Significant Customer Information

Financial instruments which potentially subject us to concentrations of credit risk consist principally of cash, investments, and accounts receivable. As of March 31, 2013, our cash, cash equivalents and investments amounted to approximately $217.1 million. We currently invest our excess cash primarily in U.S. government and agency money market funds, and investments in corporate debt securities, U.S. treasury and government agency securities and commercial paper. As of March 31, 2013, we had approximately $21.5 million of our total $33.8 million cash and cash equivalents balance invested in institutional money market funds, of which $13.5 million was invested in a single fund, which is collateralized solely by U.S. treasury and government agency securities.

Our operations are located solely within the U.S. We are focused principally on developing, manufacturing, and commercializing Feraheme/Rienso. We perform ongoing credit evaluations of our customers and generally do not require collateral. The following table sets forth customers who represented 10% or more of our total revenues for the three months ended March 31, 2013 and 2012:

	Three Months Ended March 31,
	2013		2012
AmerisourceBergen Drug Corporation	43	%	45	%
McKesson Corporation	22	%	20	%
Cardinal Health, Inc.	15	%	15	%
Takeda Pharmaceuticals Company Limited	12	%	11	%

In addition, approximately 30% and 35% of our end-user demand during the three months ended March 31, 2013 and 2012, respectively, was generated by members of a single GPO with which we have contracted. Revenues from customers outside of the U.S. amounted to approximately 12% and 11% of our total revenues for the three months ended March 31, 2013 and 2012, respectively, and were related to collaboration revenue recognized in connection with our collaboration agreement with Takeda, which is based in Japan.