HONG KONG (BLOOMBERG) - A snack maker suddenly tumbled the most in more than a year in Hong Kong, with traders speculating that someone may have mistakenly sold the stock.

Want Want China Holdings Ltd lost as much as 7.8 per cent just as the pre-market session opened, with some 101,000 shares changing hands at the intra-day low of HK$5.65, according to data compiled by Bloomberg. Want Want, a member of the Hang Seng Index, erased the losses within minutes after regular trading started, rising 0.3 per cent at 11.02am local time.

Possible explanations included a trading error known as a "fat finger". Others guessed it was a case of mistaken identity: Want Want's Chinese name shares three out of its four characters with China Zhongwang Holdings Ltd, which tumbled as much as 21 per cent after its billionaire owner was charged with evading US tariffs.

"It could be someone's mistake, but it could also be some investors' own judgment over the stock," said Mr Jackson Wong, asset management director at Amber Hill Capital Ltd. "It's quite a big discount for Want Want. That deal was the biggest in the pre-market."

Hong Kong Exchanges & Clearing Ltd didn't immediately reply to an e-mail seeking comment on the trades. A marketing representative for Want Want in Taipei declined to comment on the stock move, referring queries to the Shanghai office.