The Toronto Stock Exchange (TSX) has said it is looking into Canadian frozen dessert company CoolBrands to determine whether or not the company broke any rules by not informing the exchange before making an announcement that affected the value of its shares.

The price of CoolBrands' shares fell 43% after it announced that its licence agreement with Weight Watchers International would come to an end on 28 September after the two companies failed to agree on terms for an extension, reported Reuters.

TSX spokesman Steve Kee said the stock exchange was looking into the matter and may consider taking action against the firm if the investigation points to any wrongdoing.

"We may provide a written reprimand, we may require the company to come in for an education session. We might refer the case back to the securities commission if any securities laws were broken," Kee was quoted by Reuters as saying.