HSBC shares hit a 13-year low on Monday, plummeting more than 13 percent as large investors shorted the stock on hopes that the price would slide further after the rights issue.

At 6:39 a.m. British time, the stock was down 13.2 percent at HK$37.70 as the bank heads towards its deeply discounted rights issue this week.

The stock dragged down the main index .HSI which was down 2.6 percent, after ending the morning session 1.8 percent lower.

Last week, HSBC announced plans to raise $17.7 billion (12.56 billion pounds) through a rights issue priced at HK$28 in Hong Kong to shore up its balance sheet. The stock went into a tailspin, shedding 24 percent on the week and wiping $21 billion off its market value.