abiomed , inc . and subsidiaries notes to consolidated financial statements 2014 ( continued ) the calculation of diluted weighted-average shares outstanding for the fiscal years ended march 31 , 2004 , 2005 and 2006 excludes potential stock from unexercised stock options that have an exercise price below the average market price as shown below . year ended march 31 , potential dilutive shares from exercise of common stock options .
for the available-for 2013sale securities , what is the unrealized gain or loss at march 31 , 2005?
the calculation of diluted weighted average shares outstanding excludes unissued shares of common stock associated with outstanding stock options that have exercise prices greater than the average market price . for the fiscal years ending march 31 , 2004 , 2005 and 2006 , the weighted average number of these potential shares totaled 1908347 , 825014 and 1417130 shares , respectively . the calculation of diluted weighted average shares outstanding for these fiscal years also excludes warrants to purchase 400000 share of common stock issued in connection with the acquisition of intellectual property ( see note 5 ) . ( k ) cash and cash equivalents the company classifies any marketable security with a maturity date of 90 days or less at the time of purchase as a cash equivalent . at march 31 , 2005 and march 31 , 2006 , the company had restricted cash of approximately $ 97000 and $ 261000 , respectively , which are included in other assets at march 31 , 2005 and prepaid expenses and other current assets at march 31 , 2006 , respectively . this cash represents security deposits held in the company 2019s european banks for certain facility and auto leases . ( l ) marketable securities and long-term investments the company classifies any security with a maturity date of greater than 90 days at the time of purchase as marketable securities and classifies marketable securities with a maturity date of greater than one year from the balance sheet date as long-term investments based upon the ability and intent of the company . in accordance with statement of financial accounting standards ( sfas ) no . 115 , accounting for certain investments in debt and equity securities , securities that the company has the positive intent and ability to hold to maturity are reported at amortized cost and classified as held-to-maturity securities . at march 31 , 2006 the held-to-maturity investment portfolio consisted primarily of government securities and corporate bonds with maturities of one year or less . the amortized cost , including interest receivable , and market value of held 2013to-maturity short-term marketable securities were approximately $ 29669000 and $ 29570000 at march 31 , 2005 , and $ 16901000 and $ 16866000 at march 31 , 2006 , respectively . the company has classified its portion of the investment portfolio consisting of corporate asset-backed securities as available-for 2013sale securities . the cost of these securities approximates market value and was $ 4218000 at march 31 , 2005 and $ 6102000 at march 31 , 2006 . principal payments of these available-for-sale securities are typically made on an expected pre-determined basis rather than on the longer contractual maturity date. .