No tender offeror (including his or her related persons and tender offer agent) shall purchase the relevant stocks, etc. other than through the tender offer from the public notice date of the tender offer until the end of the tender offer period: Provided, That such purchase, etc. may be allowed, if there is no possibility of undermining other shareholder's interests, in circumstances prescribed by Presidential Decree, even if the relevant stocks, etc. are purchased other than through the tender offer.