The world's second biggest drugmaker said on Friday it sold 5,749,157 shares between March 17 and 19, leaving it with 30,755,151 or around 16.5 percent of the company, with a market value of approximately $1.36 billion.

"The shares were sold as part of a gradual reduction in the group's holding and to take advantage of Quest's recently expanded share repurchase programme," Glaxo said.

Glaxo originally bought into Quest after selling its clinical laboratories business to the U.S. company in 1999.

(Reporting by Ben Hirschler; Editing by David Cowell)

LONDON (Reuters)