Saudi Arabia's Olayan Group's stake in bank Credit Suisse has fallen by more than 25 per cent since the end of 2014, according to information provided by the SIX Swiss Exchange in Zurich on Wednesday.

Olayan owns 4.95 per cent of Credit Suisse, the second-biggest Swiss bank. It had previously held 6.7 per cent of Credit Suisse shares, according to the bank's 2014 annual report.

The reduced shareholding comes as Credit Suisse's new Chief Executive Officer Tidjane Thiam leads an overhaul that included a private placement with 37 investors, who provided the bank with some 1.35 billion Swiss francs ($1.32 billion) as part of a capital increase plan.

If Olayan declined to participate or did not participate proportionate to its previous stake, then its holding as a per centage of total ownership would have fallen.

Credit Suisse declined to comment on Olayan's holdings. Olayan also declined to comment. – Reuters