Ask.com CEO Jim Lanzone is quitting after six years with the company, to join a venture capital firm. His replacement, Jim Safka, currently heads Primal Ventures, the venture capital division of Ask.com's parent company IAC.

The moves are intended to streamline the operating structure of IAC as it prepares to spin off some of its operations, said Barry Diller, CEO of IAC.

The group plans to turn its HSN (Home Shopping Network), Ticketmaster, Interval International, and LendingTree activities into separate, publicly traded companies.

Lanzone was responsible for a "turnaround" at Ask.com over the last two years, Diller said in a statement.

However, Ask.com's share of the U.S. search market is small: it had just 4.6 percent of the market in November, compared to 9.8 percent for Microsoft, 22.4 percent for Yahoo, and 58.6 percent for Google, according to market watcher Comscore. Ask.com's share has fallen from 5.2 percent in March, according to Comscore figures.

Ask.com is going down fighting, though: in November, it struck a deal with Google said to be worth up to $3.5 billion to display sponsored search listings for its larger rival.

It has also tried to differentiate itself from the other search engines by promising to protect its users' privacy and erase personal data stored about the searches they make.

Ask.com's new CEO Safka will be aided by Scott Garell who, in the role of president, will manage Ask.com's daily business operations, the company said. Garell is currently head of IAC's consumer applications and portals business, which includes the Evite service.

Ex-CEO Lanzone become an entrepreneur-in-residence at Redpoint Ventures. That company's past investments include Excite, MySpace, TiVo -- and Ask.com itself.