The acquisition of securities of an issuer by a person who, prior to such acquisition, was a beneficial owner of more than five percent of the outstanding securities of the same class as those acquired shall be exempt from section 13(d) of the Act: Provided, That:
(a) The acquisition is made pursuant to preemptive subscription rights in an offering made to all holders of securities of the class to which the preemptive subscription rights pertain;
(b) Such person does not acquire additional securities except through the exercise of his pro rata share of the preemptive subscription rights; and
(c) The acquisition is duly reported, if required, pursuant to section 16(a) of the Act and the rules and regulations thereunder.