The Company invests in agency securities, corporate securities, asset-backed securities, treasury securities and other securities. The following is a summary of amounts recorded on the Consolidated Balance Sheet for marketable securities (current and non-current).

		March 31,		December 31,
(Millions)		2015		2014

U.S. government agency securities		$	67	$	67
Foreign government agency securities			60		75
Corporate debt securities			551		241
Commercial paper			27		―
Certificates of deposit/time deposits			24		41
U.S. municipal securities			3		―
Asset-backed securities:
	Automobile loan related		167		122
	Credit card related		66		59
	Equipment lease related		7		21
	Other		46		―
Asset-backed securities total			286		202

Current marketable securities		$	1,018	$	626

U.S. government agency securities		$	1	$	41
Foreign government agency securities			―		20
Corporate debt securities			―		378
U.S. treasury securities			―		38
U.S. municipal securities			12		15
Asset-backed securities:
	Automobile loan related		―		160
	Credit card related		―		103
	Equipment lease related		―		27
	Other		―		46
Asset-backed securities total			―		336

Non-current marketable securities		$	13	$	828

Total marketable securities		$	1,031	$	1,454

Classification of marketable securities as current or non-current is dependent upon management's intended holding period, the security's maturity date and liquidity considerations based on market conditions. If management intends to hold the securities for longer than one year as of the balance sheet date, they are classified as non-current. The classification as of March 31, 2015, was impacted by the February 2015 announcement that 3M has entered into a definitive agreement with Polypore International Inc. to acquire Polypore's Separations Media business (discussed in Note 2).

At March 31, 2015, gross unrealized losses were immaterial, while gross unrealized gains totaled approximately $1 million (pre-tax). At December 31, 2014, gross unrealized losses totaled approximately $1 million (pre-tax), while gross unrealized gains totaled approximately $1 million (pre-tax). Refer to Note 4 for a table that provides the net realized gains (losses) related to sales or impairments of debt and equity securities, which includes marketable securities. The gross amounts of the realized gains or losses were not material. Cost of securities sold use the first in, first out (FIFO) method. Since these marketable securities are classified as available-for-sale securities, changes in fair value will flow through other comprehensive income, with amounts reclassified out of other comprehensive income into earnings upon sale or “other-than-temporary” impairment.

3M reviews impairments associated with its marketable securities in accordance with the measurement guidance provided by ASC 320, Investments-Debt and Equity Securities, when determining the classification of the impairment as “temporary” or “other-than-temporary”. A temporary impairment charge results in an unrealized loss being recorded in the other comprehensive income component of shareholders' equity. Such an unrealized loss does not reduce net income attributable to 3M for the applicable accounting period because the loss is not viewed as other-than-temporary. The factors evaluated to differentiate between temporary and other-than-temporary include the projected future cash flows, credit ratings actions, and assessment of the credit quality of the underlying collateral, as well as other factors.

The balances at March 31, 2015 for marketable securities by contractual maturity are shown below. Actual maturities may differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties.

(Millions)	March 31, 2015

Due in one year or less	$	357
Due after one year through five years		654
Due after five years through ten years		5
Due after ten years		15

Total marketable securities	$	1,031

3M has a diversified marketable securities portfolio of $1.031 billion as of March 31, 2015. Within this portfolio, current and long-term asset-backed securities (estimated fair value of $286 million) primarily include interests in automobile loans, credit cards and equipment leases. 3M's investment policy allows investments in asset-backed securities with minimum credit ratings of Aa2 by Moody's Investors Service or AA by Standard & Poor's or Fitch Ratings or DBRS. Asset-backed securities must be rated by at least two of the aforementioned rating agencies, one of which must be Moody's Investors Service or Standard & Poor's. At March 31, 2015, all asset-backed security investments were in compliance with this policy. Approximately 92.2 percent of all asset-backed security investments were rated AAA or A-1+ by Standard & Poor's and/or Aaa or P-1 by Moody's Investors Service and/or AAA or F1+ by Fitch Ratings. Interest rate risk and credit risk related to the underlying collateral may impact the value of investments in asset-backed securities, while factors such as general conditions in the overall credit market and the nature of the underlying collateral may affect the liquidity of investments in asset-backed securities. 3M does not currently expect risk related to its holding in asset-backed securities to materially impact its financial condition or liquidity.