Singapore Exchange (SGX) is making some changes to the way it queries companies about unusual fluctuations in the trading of their stocks.

Following a joint review with the Monetary Authority of Singapore, the SGX will enhance its public query process by providing further guidance and details in the public query. The bourse operator will now provide examples as a guide, of yet-to-be disclosed information that could explain the trading patterns.

It will also require the company's board of directors to approve the company's reply to SGX's query.

SGX will then publish a "Trade with Caution" announcement if companies are unable to explain the trading activities which they were queried about.

And companies will have to notify SGX of discussions or negotiations that are likely to lead to a takeover, reverse takeover or a very substantial acquisition.

These companies are also required to keep a list of names of persons privy to the transaction.

These changes take effect on March 3.

Separately, SGX said it is revising the fee structure for stocks trading, in a bid to lower costs and improve liquidity in the market.

The revisions to clearing and depository fees will be rolled out from May 2, the bourse operator said yesterday.

The clearing fee will be reduced by one-fifth from 0.04 per cent to 0.0325 per cent of contract value. The cap of $600 on this fee for contracts of $1.5 million or more, will be removed.

Transfers and onward settlement fees, which are mainly levied on brokers and depository agents, will also be revised. Transfers and onward settlements for on-exchange trades will be charged a fee of $30 and transfers and settlements for off-exchange trades will be charged a fee of 0.015 per cent of the value of the transaction, subject to a minimum of $75.