3M Co. on Monday said that it would extend its $943 million tender offer for Cogent Inc. a few more days, after accumulating more than 70 percent of outstanding shares last week.

Ventura Acquisition Corp., a subsidiary of the St. Paul, Minn. conglomerate, is offering $10.50 per share until 3 p.m. Pacific time Tuesday. As of Friday, 16.7 million shares were tendered, with the company now owning about 63.1 million Cogent shares.

This is the second time 3M has extended its offer. The company had acquired 52 percent of shares by the time the first offer expired on Oct. 7.

3M first made its offer on Aug. 30. The deal has been hindered by some of Cogent’s largest shareholders, who went to court to block it and make the company consider a $12-a-share bid from NEC Corp. Cogent has argued that the offer was not firm enough at the time, and has been successful in convincing judges to let the 3M offer proceed.

Shares were down 1 cent, or less than a percent, to $10.50 in midday trading on the Nasdaq.