million of shares of our common stock and our cash dividend payments totaling $186.5 million. These uses of cash were offset by cash proceeds of $153.5 million from common stock issued under our employee stock plans. Cash provided by financing activities increased in fiscal year 2014 due primarily to the net proceeds of $1.48 billion we received from the convertible note offering that was completed during the fourth quarter of fiscal year 2014, as well as cash proceeds of $70.2 million from common stock issued under our employee stock plans. Concurrent with the convertible note offering, we used net proceeds of $108.0 million to fund the related note hedge and warrant transactions. During fiscal year 2014, we also used $887.3 million to repurchase shares of our common stock and paid $181.3 million of cash dividends to shareholders.

Liquidity



Our primary source of liquidity is cash generated by our operations. Our investment portfolio consists principally of cash and cash equivalents, debt securities of corporations and United States government and its agencies, asset-backed securities, mortgage-backed securities issued by government-sponsored enterprises, money market funds and foreign government bonds. These investments are denominated in United States dollars. As of January 25, 2015, we did not have any investments in auction-rate preferred securities.



Please refer to Note 7 of the Notes to the Consolidated Financial Statements in Part IV, Item 15 of this Annual Report on Form 10-K for additional information.



As of January 25, 2015 and January 26, 2014, we had $4.62 billion and $4.67 billion, respectively, in cash, cash equivalents and marketable securities. Our investment policy requires the purchase of high grade investment securities and the diversification of asset types and includes certain limits on our portfolio duration, as specified in our investment policy guidelines. These guidelines also limit the amount of credit exposure to any one issue, issuer or type of instrument. As of January 25, 2015, we were in compliance with our investment policy. As of January 25, 2015, our investments in U.S. government agencies and U.S. government sponsored enterprises represented 35% of our total investment portfolio, while the financial sector accounted for 30% of our total investment portfolio. All of our investments are with A/A3 or better rated securities.



We performed an impairment review of our investment portfolio as of January 25, 2015.  Based on our quarterly impairment review, we concluded that our investments were appropriately valued and did not record any impairment during fiscal year 2015.   



Net realized gains were $0.1 million, $2.4 million and $0.5 million for fiscal years 2015, 2014 and 2013, respectively.  As of January 25, 2015, we had a net unrealized gain of $8.4 million, which was comprised of gross unrealized gains of $11.0 million, offset by $2.6 million of gross unrealized losses.  As of January 26, 2014, we had a net unrealized gain of $4.8 million, which was comprised of gross unrealized gains of $7.2 million, offset by $2.4 million of gross unrealized losses. 



Our accounts receivable are highly