HONG KONG, Dec 7 — CITIC Securities Co Ltd is not able to contact two of its top executives, China’s biggest brokerage said yesterday, following media reports that the executives had been asked by authorities to assist in an investigation.

CITIC said in a filing to the Hong Kong exchange it could not reach two of its most senior investment bankers, Jun Chen and Jianlin Yan. Chinese business publication Caixin said on Friday that Chen and Yan had been detained, although it was not clear whether they were subjects of an investigation or merely being asked to assist with it.

CITIC Securities is among Chinese brokerages facing investigation by the country’s securities regulator for suspected breaches of rules.

Some employees of CITIC Securities have returned to work after assisting with unspecified government investigations, the company said in the filing.

Chen is head of CITIC’s investment banking division, according to the company website, while Yan runs investment banking at the company’s overseas unit CITIC Securities International.

Several high-profile brokerage executives have been investigated in mainland China as authorities looked for answers to explain a slump of more than 40 per cent in stocks between June and August that they blamed in part on “malicious short-selling”.

Executives at CITIC Securities have been investigated for insider trading and leaking information.

Last month, CITIC said it was choosing a new chairman and incumbent Wang Dongming could not take part because of his age. However, the Financial Times reported that Wang had been forced out because of the scandal, citing people familiar with the matter.

Authorities have revealed little about the specific reasons for the probes, but sources have told Reuters they believed some of the investigations involved suspicions of insider trading relating to trades by China’s “national team” — the big brokerages and fund managers dragooned into buying stocks as part of unprecedented measures to prop up the market. — Reuters