The former boss of the Morrisons supermarket chain has been fined GBP210,000 (US$345,600) by the Financial Services Authority for failing to disclose when he sold shares worth more than GBP400m.

The FSA said 79-year-old Sir Ken, who retired in 2008, had not revealed that he sold the majority of his shares – cutting his holding in the supermarket chain from more than 6% to 0.9% – throughout 2009 and 2010.

The financial watchdog stipulates that a significant shareholder in a business must notify the company of all share sales within two days of the transaction happening.

Additionally, the company must then make the disclosure public no later than the following day. The share sales were only made clear to the markets in March 2011.

Morrison, whose father founded the Bradford-based chain, had not benefited financially, according to the FSA, but his failure to notify the company of the changes prevented it from updating the stock market in line with stock exchange rules.

His fine was reduced from GBP300,000 after he cooperated with the investigation and agreed to settle early.

Tracey McDermott, the regulator’s acting director of enforcement and financial crime, said yesterday (16 August) that investors were entitled to know when major shareholders significantly cut their stake in a listed company. She said: “Ken should have been aware of his obligations and his failure to meet them has resulted in this fine.”

A spokesman for Morrisons said: “This is a matter between Sir Ken and the FSA so we won’t be commenting.”