An issuer shall, if the issue of new securities by it or the purchase by it of its listed securities will result in a change in the terms of conversion of any of its convertible securities or in the terms of the exercise of any of its options, warrants or similar rights, publish an announcement in accordance with rule 2.07C as to the effect of any such change wherever practicable, prior to the new issue and, if not so practicable, as soon as possible thereafter.