By Iain Withers

LONDON (Reuters) -Shares in Barclays fell as much as 6% in early trading on Tuesday, after one of its top investors offloaded stock roughly equivalent to a 3% stake in the lender.

An unnamed investor launched a sales process for 575 million shares on Monday evening, facilitated by Goldman Sachs.

The offering was priced at 150 pence on Tuesday, towards the top of the target range of 147.50 pence to 150.75 pence, but this still represented a discount greater than 6% to Monday’s closing price, heaping pressure on the share price.

Barclays shares opened down around 6%, near the sale price, before clawing back some ground. The stock was last down 4.3% at 153.5 pence at 0727 GMT.

Top shareholders with around a 3% stake in Barclays include the Qatar Investment Authority and Blackrock, according to Refiniv Eikon data. Blackrock declined to comment when approached by Reuters on Monday, while QIA was not immediately available for comment.

The sale comes as Barclays grapples with a fresh compliance and risk mis-step, after it disclosed an estimated 450 million pound ($589 million) loss on Monday due to overselling structured products in the United States.

The disclosure had already pressured Barclays’ stock this week, leading to a 4% fall on Monday.

Barclays also said it would have to delay a planned 1 billion pound share buyback because of the loss, which it will have to incur as a result of buying back the securities in question at their original purchase price.

The regulatory blunder is an early test for C.S. Venkatakrishnan, the newly-appointed chief executive of Barclays, whose previous roles included heading the bank’s global markets and risk operations.

($1 = 0.7640 pounds)

(Reporting by Iain Withers, editing by Sinead Cruise and Emelia Sithole-Matarise)