Among the movers in Monday's very quiet and thinly traded late session were oil drillers

Transocean

(RIG) - Get Report

and

GlobalSantaFe

(GSF)

.

Shares saw heavy postclose volume after the U.K.'s Office of Fair Trading cleared the merger-of-equals that the Houston-based companies agreed to earlier this year, having mollified certain of the regulators' antitrust concerns. The companies say they expect the merger to close Tuesday -- the originally scheduled date -- in light of the news.

Transocean shares were down 0.8% to $128.45. GlobalSantaFe lately ticked up 33 cents to $87.16.

Other after-hours winners included drugmaker

Bristol Myers Squibb

(BMY) - Get Report

, up 1.7% to $28.07; closeout retailer

Big Lots

(BIG) - Get Report

, up 0.4% to $20.40; and real estate investment trust

Apartment Investment & Management

(AIV) - Get Report

, which added 2.8%.

The decliners included

Pharmacopeia

( PCOP), which slid 7.2% to $4.15; auctioneer

Sotheby's

(BID) - Get Report

, down 2.2% to $34.25; and clinical-research company

Kendle International

( KNDL) which was off 88 cents, or 2.1%, to $41.50.