BELLEVUE, Wash (AP) -- Shares of vending machine operator Coinstar, Inc. plunged nearly 30 percent in aftermarket trading Thursday after the company lowered its earnings estimate for the fourth quarter on disappointing sales at its chain of Redbox DVD-rental kiosks.

Coinstar said its holiday revenues were surprisingly low after a slew of movies were delayed for rental by 28 days. While customer traffic at the kiosks remained strong, people rented fewer DVDs with each trip, and revenue came in far below expectations, the company said.

The company said it expects to report fourth-quarter revenue of $391 million. It had initially forecast revenue between $415 million to $440 million. The company now estimates earnings per share between 65 and 69 cents a share, rather than the previously predicted range of 79 to 85 cents a share.

Analysts expect earnings of 86 cents a share on revenue of $426.1 million, according to a FactSet poll.

Chief Executive Officer Paul Davis said a number of factors contributed to the shortfall. He said an unexpectedly high share of customers utilized the option to rent DVDs from one kiosk and return them to another, creating an imbalance of supply. At the same time, 2010 was the first holiday season when a slate of movies had been delayed for rental by 28 days. Davis said Coinstar anticipated demand would be higher for those movies than it really was.

"We have already taken a number of decisive steps to better align content purchases with our consumers' behavior, including offering more day and date titles and better allocating Blu-ray titles to high demand areas," Davis said in a statement.

The company said its earnings per share estimates for the quarter include a reduction of 2 cents per share because of the expected increase of 1.3 million shares that will be available because of the dilution from convertible debt and exercise of options. There is another 2 cent per share decline because of expenses related to the higher share price at the end of the quarter.

Coinstar reduced its outlook for full year 2011, expecting revenue between $1.7 billion and $1.85 billion, and earnings between $2.60 and $3.10 per share based on a share count of 33.3 million shares. Analysts were expecting earnings of $3.43 a share for 2011 revenue of $1.91 billion.

The company's shares fell $13.65, or 24 percent, to $43.58 during aftermarket trading following the release of the estimate. In the regular session, shares fell 28 cents to close at $56.95.