| Top Institutional Holders |
|---|
| Holder | Shares | % Out | Value* | Reported |
|---|
| Healthcor Management LP | 16,750,000 | 9.45 | 227,632,500 | Mar 31, 2013 | | Wellington Management Company, LLP | 16,394,484 | 9.25 | 222,801,037 | Mar 31, 2013 | | Vanguard Group, Inc. (The) | 8,377,917 | 4.73 | 113,855,892 | Mar 31, 2013 | | Vista Equity Partners III, LLC | 6,880,075 | 3.88 | 93,500,219 | Mar 31, 2013 | | Goldman Sachs Group, Inc. | 6,227,243 | 3.51 | 84,628,232 | Mar 31, 2013 | | Blue Harbour Group, LP | 5,949,099 | 3.36 | 80,848,255 | Mar 31, 2013 | | BlackRock Institutional Trust Company, N.A. | 4,628,304 | 2.61 | 62,898,651 | Mar 31, 2013 | | State Street Corporation | 4,284,144 | 2.42 | 58,221,516 | Mar 31, 2013 | | RS Investment Management Co., LLC | 4,150,202 | 2.34 | 56,401,245 | Mar 31, 2013 | | Tradewinds Global Investors, LLC | 4,107,281 | 2.32 | 55,817,948 | Mar 31, 2013 |
|
| Holder | Shares | % Out | Value* | Reported |
|---|
| Vanguard Specialized-Health Care Fund | 4,005,709 | 2.26 | 44,383,255 | Jan 31, 2013 | | Blackrock Funds-Small Cap Growth Equity Portfolio | 3,672,928 | 2.07 | 34,598,981 | Dec 31, 2012 | | Hartford Mid Cap Fund | 2,360,820 | 1.33 | 30,006,022 | Feb 28, 2013 | | RS Investment Trust-Partners Fund | 2,196,932 | 1.24 | 29,856,305 | Mar 31, 2013 | | Vanguard Explorer Fund, Inc. | 2,189,600 | 1.24 | 24,260,768 | Jan 31, 2013 | | Vanguard Total Stock Market Index Fund | 2,175,365 | 1.23 | 20,491,938 | Dec 31, 2012 | | Vanguard Mid-Cap Index Fund | 2,127,386 | 1.20 | 20,039,976 | Dec 31, 2012 | | iShares Core S&P Midcap Index Fund | 1,948,009 | 1.10 | 26,473,442 | Mar 31, 2013 | | SPDR S&P Mid Cap 400 ETF Trust | 1,564,551 | 0.88 | 21,262,248 | Mar 31, 2013 | | Vanguard Extended Market Index Fund | 1,424,069 | 0.80 | 13,414,729 | Dec 31, 2012 |
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View Transactions for Insiders & Institutional Holders Value shown is computed using the security's price on the report date given. Currency in USD. |