TNT - further down before up!

In the past few years, several cyber security firms such as FireEye Inc (FEYE.O), Rapid7 Inc (RPD.O) and Mimecast Ltd (MIME.O) have gone public to take advantage of growing investor interest in them after a spate of hacking attacks on companies including major banks and retailers.

However, shares of Rapid7 and FireEye, which popped 70-80 percent in their debut, are now trading way below their IPO prices. Mimecast, which jumped 20 percent on its listing day, has also slipped below its offering price.

Ritter warned against premium pricing for stocks of cyber security firms, saying that these companies were fighting for market share, which would keep their profit growth muted.