Pfizer

(PFE) - Get Report

cleared the last major obstacle to its acquisition of

Pharmacia

(PHA)

, receiving clearance for the deal from the Federal Trade Commission.

Pfizer said the two companies will start operating as a combined unit later this week. While the FTC did require the divestiture of some products, they "weren't material," Pfizer added.

"The rigorous review process concluded that the companies were highly complementary with few overlaps," Pfizer said. The two companies announced the $60 billion acquisition last summer.

Shares of Pharmacia were up 50 cents to $44.39, while shares of Pfizer rose 23 cents to $31.74.