The Los Angeles Business Journal’s index of largest local public companies closed up for the week, in line with the S&P 500 having its best week this year.

The weighted LABJ Stock Index closed up 3.9 percent to 126.24 for the week ended June 8. Gainers outpaced decliners 97 to 70, with eight companies unchanged.

The most volatile stock for the week was Molina Healthcare Inc., which ended the week down 12 percent to $22.46. The Long Beach Medicaid managed care company fell 31 percent on Thursday after withdrawing its full-year earnings forecast due to problems in its large Texas market. But the stock rebounded more than 25 percent on Friday after the company said it won its appeal to continue as a carrier in Ohio, one of its largest markets.

OriginOil Inc. fell 13 percent to $1.01. The Los Angeles developer of technology to create algae-based fuels said it is gearing up for commercial rollout of a clean-up process for oil and gas wastewater. It selected Clean Water Technology of Los Angeles to manufacture the systems.

Among the biggest gainers was Tix Corp., which rose 14 percent to $2. Mitch Francis, chairman and chief executive of the Studio City discount tickets seller, offered to take the company private in a cash offer of $2.25 a share.

Skechers USA Inc. rose 13.4 percent to $19.29. The Manhattan Beach shoemaker committed to purchasing ad time for the 2013 Super Bowl.

Obagi Medical Products Inc. gained 13 percent to $14. Shareholders of the Long Beach skin-care company rejected a “poison pill” shareholders-rights plan at the company’s annual meeting.