MARKETABLE SECURITIES

12 Months Ended

Dec. 31, 2021

NOTE 5. MARKETABLE SECURITIES

A summary of marketable securities, all of which are classified as current, was as follows:


	December 31,
	2021						2020
In millions	Cost		Gross unrealized gains/(losses) (1)		Estimated fair value		Cost		Gross unrealized gains/(losses) (1)		Estimated fair value
Equity securities





Certificates of deposit	$	299	$	—	$	299	$	164	$	—	$	164
Debt mutual funds	254		2		256		267		5		272
Equity mutual funds	29		10		39		19		5		24


Debt securities	1		—		1		1		—		1


Total marketable securities	$	583	$	12	$	595	$	451	$	10	$	461

(1) Unrealized gains and losses for debt securities are recorded in other comprehensive income while unrealized gains and losses for equity securities are recorded in "Other income, net" in our Consolidated Statements of Net Income.

All debt securities are classified as available-for-sale. All marketable securities presented use a Level 2 fair value measure. The fair value of Level 2 securities is estimated using actively quoted prices for similar instruments from brokers and observable inputs where available, including market transactions and third-party pricing services, or net asset values provided to investors. We do not currently have any Level 3 securities, and there were no transfers between Level 2 or 3 during 2021 or 2020.

A description of the valuation techniques and inputs used for our Level 2 fair value measures is as follows:

•Certificates of deposit— These investments provide us with a contractual rate of return and generally range in maturity from three months to five years. The counterparties to these investments are reputable financial institutions with investment grade credit ratings. Since these instruments are not tradable and must be settled directly by us with the respective financial institution, our fair value measure is the financial institution's month-end statement.

•Debt mutual funds— The fair value measures for the vast majority of these investments are the daily net asset values published on a regulated governmental website. Daily quoted prices are available from the issuing brokerage and are used on a test basis to corroborate this Level 2 input measure.

•Equity mutual funds— The fair value measures for these investments are the net asset values published by the issuing brokerage. Daily quoted prices are available from reputable third-party pricing services and are used on a test basis to corroborate this Level 2 input measure.

•Debt securities— The fair value measures for these securities are broker quotes received from reputable firms. These securities are infrequently traded on a national exchange and these values are used on a test basis to corroborate our Level 2 input measure.

The proceeds from sales and maturities of marketable securities were as follows:


	Years ended December 31,
In millions	2021		2020		2019
Proceeds from sales of marketable securities	$	494	$	343	$	258
Proceeds from maturities of marketable securities	179		126		131
Investments in marketable securities - liquidations	$	673	$	469	$	389