RIYADH, (Reuters) – The Saudi regulator, CMA, has imposed fines of up to $27,000 on three firms for breaching disclosure rules, as it tries to polish the image of an opaque bourse gradually opening up to foreign investors.

It brought to 13 the number of companies fined for violating disclosure regulations since May 16.

Al Baha Investment and Development Co was fined 100,000 riyals ($27,000) for disclosing acquisition plans to the Capital Market Authority after they were leaked to a website, the CMA said.

Methanol Chemicals Co (Chemanol) 2001.SE was also fined 100,000 riyals and Saudi International Petrochemical Co (2310.SE: Quote, Profile, Research, Stock Buzz) was fined 50,000 for other disclosure violations.

Like others in the Gulf region, Saudi Arabia’s stock exchange has been dogged by allegations it is opaque and subject to manipulation of stock prices, and the regulator has slapped fines on investors and executives for violations.

The bourse is gradually opening up to direct foreign ownership amid tough competition from regional bourses.

Over the past two years, CMA has stepped up efforts to clamp down on irregularities, imposing one jail sentence and revoking the licences of several brokerage firms for violations.