Shares of

Priceline.com

(PCLN)

dropped after news that the head of its auto-services business, Maryanne Keller, resigned.

Shares of the troubled name-your-own-price Internet company were recently down 75 cents, or 18.4%, to $3.50.

According to a report in

The Wall Street Journal

, Keller said she thinks the experiment of selling cars online failed, saying it was "an idea whose time has not yet come, and may never."

When contacted, Priceline.com refused to comment on the reasons for Keller's resignation. The company's chief financial officer, Heidi Miller, left the company last week.

The company said Pamela Caputo, a former car dealer with Internet auto sales experience, has replaced Keller as vice president of automotive sales.