Actifio, a Waltham data storage company, became the latest hot technology start-up to gear up for an initial public offering after it raised a new round of funding Wednesday from venture capitalists that values the fast-growing business at $500 million.

With $50 million in new funds in its coffers, Actifio is on track to try a public offering within a year or so, its executives said, joining the Boston security firm Rapid7 Inc. and a Cambridge marketing software provider, HubSpot Inc., in the queue for Wall Street.