The Los Angeles Business Journal’s index of largest local public companies edged up slightly for the week ended Oct. 7 despite lingering investor concerns about the European economy.

The weighted LABJ index moved up 0.27 percent to close at 105.74. Decliners outpaced gainers 106 to 65, with five companies unchanged.

Among the top gainers was CyberDefender Corp., which jumped 113 percent to 66 cents. The struggling Los Angeles security software developer, which is facing delisting, appointed a new chief executive and secured $3.45 million in new financing.

Stamps.com gained 16 percent to $24.72. More than double the normal volume of shares in the Los Angeles online postage company changed hands on Friday as the company hit a new 52-week high. Plans for cuts at the U.S. Postal Service have made the company look attractive to investors.

Among the biggest decliners was Vitesse Semiconductor Corp., which dropped 20 percent to $2.36. The Camarillo chip maker revised its fourth quarter revenue guidance downward based on market conditions.

Wesco Aircraft Holdings Inc., which went public in July, fell 19 percent to $8.95. Two analysts initiated coverage on the Valencia aerospace equipment supplier with “hold” or “neutral” ratings, offsetting a third analyst who had a more upbeat overweight” rating on shares.

Derycz Scientific Inc. fell 12 percent to $1.40. The Santa Monica online publisher of scientific papers reported a net loss for fiscal 2011.