LOS ANGELES (AP) â¿¿ Arden Group Inc., the parent of Southern California supermarket chain Gelson's Markets, said Wednesday that its third quarter net income plunged 26 percent, as the economy and competition hurt sales. The company earned $3.5 million, or $1.09 per share, in the three months that ended Oct. 2. That compares to net income of $4.7 million, or $1.48 per share, in the same quarter of 2009. Revenue fell 3 percent to $100.3 million. Sales at stores open at least a year, considered a key indicator of a retailer's financial health fell, 3.3 percent in the quarter. Grocers across the industry have been struggling with price cuts by competitor Wal-Mart Stores Inc., along with high unemployment and a weak housing market. Shares of Arden climbed 5 percent, or $4.56, to $93 in Wednesday afternoon trading.