The Los Angeles Business Journal’s index of the largest local public companies closed down for the week ended May 7 after a week of extreme stock market volatility and some disappointing local corporate news.

The weighted LABJ index closed down 3.5 percent to 118.34, with decliners outpacing gainers 155 to 26.

K-Swiss Inc. shares slid more than 32 percent after the Westlake Village athletic-shoe maker reported a smaller-than-expected first quarter loss but warned that an overseas plant closure would hurt sales for the rest of this year.

The market turmoil hit downtown L.A. office landlord Maguire Properties Inc., which fell 31 percent to $2.70. Despite no market-moving news about the company, its stock topped the list of biggest percentage price decliners Friday on the New York Stock Exchange.

Guess Inc. fell more than 21 percent to $37.61 after the Los Angeles apparel and accessories company said Chief Operating Officer Carlos Alberini was resigning to become co-chief executive of Restoration Hardware in the Bay Area city of Corte Madera.

DineEquity Inc. ended the week down 21 percent to $33.89 after the Glendale owner of the Applebee’s Neighborhood Grill & Bar and IHOP restaurant chains reported a disappointing first quarter.

Among the best performers was Los Angeles real estate developer Portsmouth Square, Inc., which jumped 23 percent to $ 23.50, despite no market-moving announcements.

Power-One Inc. gained 21 percent to $7 after the Camarillo power management company reported promising first quarter earnings.