The Los Angeles Business Journal’s index of largest local public companies rose for the week ended May 13 as investors reacted to conflicting economic reports.

The weighted LABJ index closed up 1.72 percent to 129.18, with decliners outpacing gainers 106 to 79.

Among the biggest decliners was Obagi Medical Products Inc., which fell 22 percent to $10.00. The Long Beach medical skin care company was hurt by analyst concerns following a first quarter net loss.

Wilshire Bancorp Inc. dropped 11 percent $3.20, after the Koreatown bank holding company commenced a dilutive stock offering.

Boingo Wireless Inc. fell 8.6 percent to $10.75, as the Santa Monica-based Wi-Fi network operator’s stock continued to find its equilibrium following a May 3 initial public offering.

Despite reporting a narrower first-quarter loss, MannKind Corp. fell 8.5 percent to $2.99. Investors worried about continued delays in the Valencia biotech efforts to obtain U.S. regulatory approval for its inhaled insulin product.

Among the biggest gainers was Power-One Inc., which rose more than 10 percent to $8.85. Despite worries about a slower market for its products in Europe, the Camarillo solar inverter maker reported first quarter profit that was in line with Wall Street estimates.

American Apparel Inc. rose 9.8 percent to $1.12. The struggling Los Angeles apparel maker and retailer reported a smaller loss in the first quarter and said same-store sales should be up for the full year.

Hot Topic Inc. rose nearly 9 percent to $7.96. The City of Industry teen retailer reported a sharp rise in same-store sales last month.