NantKwest, an immunotherapy company in Culver City, was one of the week’s leading gainers on the Los Angeles Business Journal’s Stock Index of local companies, with shares up 25 percent to close at $8.14. The firm is known for using “natural killer” cells to treat cancer, infectious diseases and inflammatory diseases.

Woodland Hills Internet service provider United Online Inc. also had a good week. Shares rose 23 percent to close at $12 a share.

Differential Brands Group, a downtown Los Angeles apparel firm, was one of the week’s biggest losers. Shares fell 13percent to close the week at $4.50.