Hong Kong’s securities watchdog warned the city’s brokers after finding examples of inadequate controls, as it escalates efforts to monitor unauthorized trading and cash movements.

Regulated banks, brokers and financial advisers had insufficient oversight of their own accounts and those of clients, the Securities and Futures Commission said in a circular posted on its website Monday.

In “a number of instances,” powerful shareholders broke rules by withdrawing funds without any oversight from the managers formally in charge, Hong Kong’s SFC found. Brokers should review existing policies and controls to bring them into line by the beginning of next year, the regulator said. It did not name individual companies.

The slap on the wrists shows how Hong Kong’s financial regulator is escalating efforts to monitor brokers in one of the world’s biggest venues for initial public offerings. Earlier this year, the securities watchdog together with the city’s stock exchange vowed to crack down on suspicious IPO activities such as inflating market capitalization, “ramp-and-dump” schemes and unusually high underwriting commissions.

In some cases, accounts beneficially owned by brokers or their clients were solely operated by a shareholder rather than an SFC-licensed responsible officer or manager-in-charge, the regulator said in the circular. In a separate case, a firm’s authorized signer had no official role and was actually a responsible officer of another regulated company.

Some Hong Kong firms seeking initial public offerings have been viewed as hotbeds for share price manipulation and insider trading, and have been at the center of high profile fraud cases and investigations. In 2019 four global investment banks agreed to pay a combined $100 million to settle cases brought by Hong Kong authorities relating to their work on initial public offerings in the city.

Read More: UBS, Other Banks Pay $100 Million to Settle Hong Kong IPO Cases

The SFC said it expects licensed firms to adopt “a formal document, approved by the board of directors, clearly setting out the firm’s management structure, including the roles, responsibilities, accountability and reporting lines of its senior management personnel.” Regulated entities have until Jan. 3, 2022, to implement the rules.