| TOP INSTITUTIONAL HOLDERS |
| Holder | Shares | % Out | Value* | Reported | | HEALTHCOR MANAGEMENT LP | 9,050,000 | 9.71 | $88,147,000 | 30-Sep-09 | | COLUMBIA WANGER ASSET MANAGEMENT, L.P. | 5,739,000 | 6.16 | $55,897,860 | 30-Sep-09 | | Barclays Global Investors UK Holdings Ltd | 5,606,848 | 6.02 | $54,610,699 | 30-Sep-09 | | VANGUARD GROUP, INC. (THE) | 3,752,080 | 4.03 | $36,545,259 | 30-Sep-09 | | GRANAHAN INVESTMENT MANAGEMENT INC. | 3,372,240 | 3.62 | $32,845,617 | 30-Sep-09 | | DRIEHAUS CAPITAL MANAGEMENT, INC. | 2,301,378 | 2.47 | $22,415,421 | 30-Sep-09 | | STATE STREET CORPORATION | 2,212,761 | 2.37 | $21,552,292 | 30-Sep-09 | | SUTTONBROOK CAPITAL MANAGEMENT LP | 1,982,600 | 2.13 | $19,310,524 | 30-Sep-09 | | RENAISSANCE TECHNOLOGIES, LLC | 1,934,500 | 2.08 | $18,842,030 | 30-Sep-09 | | OPPENHEIMER FUNDS, INC. | 18,471,554 | 19.82 | $179,912,935 | 30-Sep-09 |
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| Holder | Shares | % Out | Value* | Reported | | COLUMBIA ACORN FD | 4,631,195 | 4.97 | $30,010,143 | 30-Jun-09 | | VANGUARD EXPLORER FUND, INC. | 2,772,600 | 2.97 | $19,630,008 | 31-Jul-09 | | OPPENHEIMER GLOBAL OPPORTUNITIES FUND | 18,364,206 | 19.70 | $119,000,054 | 30-Jun-09 | | ISHARES RUSSELL 2000 INDEX FD | 1,360,501 | 1.46 | $13,251,279 | 30-Sep-09 | | VANGUARD SMALL-CAP INDEX FUND | 1,126,691 | 1.21 | $7,300,957 | 30-Jun-09 | | ISHARES NASDAQ BIOTECHNOLOGY INDEX FUND | 1,005,406 | 1.08 | $8,163,896 | 31-Oct-09 | | FEDERATED KAUFMANN FUND | 1,000,000 | 1.07 | $7,080,000 | 31-Jul-09 | | VANGUARD TOTAL STOCK MARKET INDEX FUND | 858,542 | .92 | $5,563,352 | 30-Jun-09 | | VANGUARD SMALL-CAP GROWTH INDEX FUND | 713,558 | .77 | $4,623,855 | 30-Jun-09 | | ISHARES RUSSELL 2000 GROWTH INDEX FD | 711,969 | .76 | $6,934,578 | 30-Sep-09 |
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Value shown is computed using the security's price on the report date given.
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