The Los Angeles Business Journal’s index of largest local public companies fell for the week ended Sept. 30 on continued domestic and overseas economic concerns.

The weighted LABJ index fell 0.6 percent to close at 102.68. Decliners outpaced gainers 87 to 78, with 11 companies unchanged.

The biggest decliner was OriginOil Inc., dropping 21 percent to $2.02. Falling oil prices were seen as hurting prospects for the Los Angeles alternative energy developer.

National Technical Systems Inc. fell 14 percent to $4.81. Shareholders of the Calabasas testing company rejected a shareholder proposal recommending the board hire a firm to start shopping the company to potential buyers.

Trio Tech International fell 12 percent to $2.73. The Van Nuys semiconductor testing company reported a decline in fourth quarter revenue and an overall loss for the fiscal year.

The biggest gainer was CyberDefense Corp., which jumped 24 percent to 37 cents, even though the Los Angeles security software company received another delisting notice from the Nasdaq.

MannKind Corp. continued to rally, ending the week up 18 percent to $3.76. The Valencia biotech, recently said it would sell debt rather than stock to help pay for additional drug trials for its long-delayed experimental insulin inhaler Afrezza, reassured investors by saying it believed the results could be submitted to federal regulators by early 2013.

U.S. Auto Parts Network Inc. rose 17 percent to $5.07. The Carson online distributor of aftermarket auto parts and accessories signed a lease on a larger corporate headquarters that will enable it to cut costs and improve efficiency by consolidating operations now in three buildings.