Overton had seven birdies and a 15th-hole eagle for a 9-under-par 62, breaking the record at the Mines Resort and Golf Club by one stroke. Jacobson, despite opening Friday's play with a bogey, had a second-round 7-under 64. They are at 13-under 129 after 36 holes.
Bo Van Pelt, who also shot 64 Friday, is alone in third place at 12-under and four players are tied for fourth, four strokes behind the leaders. First-round leader Robert Allenby shot 1-over 72 Friday and slipped into a tie for ninth at 7-under.
Overton opened play Friday with three consecutive birdies. He added two more at Nos. 5 and 8 in making the turn at 5-under. Overton had a birdie at 12 with a 10-foot putt that put him into the lead.
He decided to go for the green with his tee shot at the par-4, 292-yard 15th and wound up an 8-foot putt for eagle. He set the course record with a short putt at 17.
Jacobson, who eagled 15 Thursday, opened Friday with a bogey but was still 2-under after six holes. He posted four consecutive birdies from Nos. 12-15 and tied Overton with a 17th-hole birdie.