software, intangible assets and leasehold improvements at our facilities in various international locations.

   

Financing activities



Financing activities provided cash of $236.7 million, $192.0 million, and $61.1 million during fiscal years 2012, 2011, and 2010, respectively. 



Net cash provided by financing activities in fiscal year 2012 was primarily due to cash proceeds of $195.9 million from common stock issued under our employee stock plans, and a non-cash tax benefit of $52.8 million for the gross windfall related to employee stock based compensation.



Net cash provided by financing activities in fiscal year 2011 was primarily due to cash proceeds of $177.3 million from common stock issued under our employee stock plans, and a non-cash tax benefit of $15.3 million for the gross windfall related to employee stock based compensation.  



Net cash provided by financing activities in fiscal year 2010 was primarily due to cash proceeds of $138.0 million from common stock issued under our employee stock plans, offset by $78.1 million used for the purchase of outstanding stock options related to a tender offer that closed in March 2009. Please refer to Note 2 of the Notes to the Consolidated Financial Statements in Part IV, Item 15 of this Form 10-K for further discussion regarding the cash tender offer. 



Liquidity



Our primary source of liquidity is cash generated by our operations. Our investment portfolio consisted of cash and cash equivalents, commercial paper, mortgage-backed securities issued by government-sponsored enterprises, money market funds and debt securities of corporations, municipalities and the United States government and its agencies. These investments are denominated in United States dollars. As of January 29, 2012, we did not have any investments in auction-rate preferred securities.



All of the cash equivalents and marketable securities are treated as “available-for-sale”. Investments in both fixed rate and floating rate interest earning instruments carry a degree of interest rate risk. Fixed rate debt securities may have their market value adversely impacted due to a rise in interest rates, while floating rate securities may produce less income than expected if interest rates fall. Due in part to these factors, our future investment income may fall short of expectations due to changes in interest rates or if the decline in fair value of our publicly traded debt or equity investments is judged to be other-than-temporary. We may suffer losses in principal if we are forced to sell securities that decline in market value due to changes in interest rates. However, because any debt securities we hold are classified as “available-for-sale,” no gains or losses are realized in our statement of operations due to changes in interest rates unless such securities are sold prior to maturity or unless declines in market values are determined to be other-than-temporary.  These securities are reported at fair value with the related unrealized gains and losses included in accumulated other comprehensive income, a component of stockholders’ equity, net of tax.



As of January 29, 2012 and January 30, 2011, we had $3.13