(Reuters) - U.S. electronics retailer RadioShack Corp reported a much bigger-than-expected quarterly loss, hurt by higher promotions in its smart phones and tablets business and weak sales of consumer electronics.

Shares of RadioShack, which reported its ninth straight quarterly loss, plunged about 22 percent in premarket trading.

The company's sales have been falling since 2010 as it battles executive exits and tough competition from the likes of Best Buy Co Inc, Amazon.com Inc and Wal-Mart Stores Inc, who offer wider selection and lower prices.

RadioShack announced plans in March to close up to 1,100 underperforming stores. The company, however, said in May that its agreements with lenders allowed it to close fewer stores.

RadioShack's shareholders rejected its executive compensation plan for the second year in a row, a filing showed on Monday, indicating growing investor frustration with the company.

The company's net loss widened to $98.3 million, or 97 cents per share, in the first quarter ended May 3 from $28.0 million, or 28 cents per share, a year earlier.

RadioShack reported an adjusted loss of 98 cents per share.

Net sales fell 13 percent to $736.7 million.

Analysts on average had expected a loss of 52 cents per share on sales of $767.5 million, according to Thomson Reuters I/B/E/S.

Sales in stores open for at least a year fell 14 percent.

RadioShack's shares were trading at $1.20 before the bell. The stock has lost more than half its value in the year to Monday's close.

(Reporting by Devika Krishna Kumar in Bangalore; Editing by Kirti Pandey)