X0304 4 2012-02-16 0001022079 QUEST DIAGNOSTICS INC DGX 0001222679 PREVOZNIK MICHAEL E C/O QUEST DIAGNOSTICS INCORPORATED 3 GIRALDA FARMS MADISON NJ 07940 1 SVP & General Counsel Common Stock 2012-02-16 4 S 0 1462 57.3789 D 31656 D Common Stock 4371 I 401k/SDCP The sale reported was effected pursuant to a Rule 10b5-1 sales plan adopted by the reporting person on February 7, 2011. This transaction was executed in multiple trades at prices ranging from $57.37 to $57.38. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. The amount includes exempt purchases made under the Company's stock purchase plan. These underlying shares were acquired on a periodic basis by the trustee of the Company's tax qualified Profit Sharing (401(k) and/or Supplemental Deferred Compensation Plan. The information was obtain from the plan administrator as of a recent date. The number of shares is based on the account balance of the Company stock fund under the plan (which includes some money market instruments) divided by the market price of the Company's stock as of that date. /s/ William J. O'Shaughnessy, Jr., Attorney in Fact for Michael E. Prevoznik 2012-02-17