As Citigroup became the focus of fevered speculation at the end of last week, its chief executive was quick to blame "rumour mongering" among market participants as the bank called for a ban on short selling to be revived. However, the latest data show the extent of stock held on loan for the purposes of short selling do not indicate that there has been an increase in this sort of activity on Citigroup's shares.

Vikram Pandit, the bank's chief executive, quickly called a meeting with Christopher Cox, chairman of the Securities and Exchange Commission on Thursday to discuss reinstating the "uptick rule" designed to stall short sellers by limiting their upside on declining stocks. The SEC had already temporarily banned short selling on selected financial names in mid September as an emergency reaction to the bankruptcy of Lehman Brothers.