UPDATE 2-Medco to buy back $3 billion more of its shares

* Comes as earlier $3 bln buyback plan finishes

* Stock off year-high by about 12 pct

* Shares nearly unchanged (Adds share movement, analyst comment)

NEW YORK, May 13 (Reuters) - Medco Health Solutions Inc MHS.N said on Thursday that it planned to buy back $3 billion more of its stock as it finishes a share repurchase program of the same amount.

The U.S. pharmacy benefit manager's new share repurchase program, approved by Medco's board, comes as the company nears completion of its $3 billion stock buyback authorized in October 2008. Medco has a market value of about $27 billion.

Medco shares were up 2 cents at $58.84 in morning trading on the New York Stock Exchange. The stock has fallen about 12 percent from its year high of $66.84 reached in January.

While Medco intends to buy back shares "opportunistically," Chief Financial Officer Richard Rubino said: "Our core priorities for the use of our cash on hand will continue to be investing in our core business, investing in future growth initiatives and in making Medco an even more agile enterprise."

Medco said the share repurchase program did not obligate it to acquire any particular amount of stock, and the program may be suspended or discontinued at any time at its discretion.

Despite the buyback, JPMorgan analyst Lisa Gill said in a research note that Medco could still seek to acquire a pharmacy benefit unit owned by a health insurer.

Industry observers are watching to see if Medco strikes such a deal following a well-received move by rival Express Scripts Inc (ESRX.O) to buy WellPoint Inc's (WLP.N) drug benefit unit.

Since the inception of its first stock repurchase program in 2005, Medco has repurchased more than 208 million shares, the company said. (Reporting by Lewis Krauskopf; Editing by Lisa Von Ahn)