Shares of Royal Bank of Scotland plunged as much as 67 percent on Monday after investors feared the bank will be fully absorbed by the U.K. government since it forecasted a huge annual loss.

RBS stock declined the most since 1988 on Monday to 11.6 pence when the bank forecasted a loss of 28 billion pounds in 2008, the largest loss reported in U.K corporate history, Bloomberg reports.

The market is pricing in the risk of full nationalization for RBS, said Sandy Chen, an analyst at Panmure Gordon & Co. Bloomberg said.

U.K. Primer Minister Gordon Brown accused RBS on Monday for taking irresponsible risks. The government offered to exchange its preference shares in the bank for ordinary stock, a move that may increase its stake from 58 percent to near 70 percent.