NEW YORK (TheStreet) -- Shares of TrueCar (TRUE - Get Report) were falling 12.95% to $5.98 on heavy trading volume Monday, continuing the online car buying company's losses from Friday.

About 2 million shares of TrueCar were traded by 10:42 a.m. Monday, above the company's average trading volume of about 1.6 million shares a day.

Late Thursday TrueCar announced that it expects to report revenue of $65 million to $65.3 million for the second quarter, and $252 million to $258 million for full year 2015. Analysts expect TrueCar to report revenue of $66.01 million for the second quarter and $266.74 million for the year.

TrueCar's low guidance for the second quarter and full year came after a decision that led to AutoNation (AN) ending its use of the car buying service.

TrueCar said the lower guidance is due to a unit volume shortfall that results in lower-than-expected traffic growth of about 42% in the second quarter.

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