Rule 11.1.2 states that SGX-ST may cancel a contract in various circumstances including the following:
(a) if the contract arises from an Error Trade and:
(i) the Trading Members to the contract agree to the cancellation; or
(ii) SGX-ST is satisfied that the contract should be cancelled; and
(b) if the contract arises from a Trade at Close and subsequent to the trade, SGX-ST:
(i) invalidates the Closing Auction Price on which the trade is based; or
(ii) determines an alternate closing price for the security.