Navistar's stock plummeted yesterday after it announced a $172 million loss for the second quarter and that it was making management changes, calling its first-half results "unacceptable."

Navistar shares dropped 14%, the most since Aug. 8, to $24.11 at the close in New York, reports Bloomberg, and had fallen further earlier in the day. Navistar shares have dropped 36% this year after falling 35% last year.

"Certainly, our first half performance was unacceptable. It included a warranty reserve to repair early 2010 and 2011 vehicles," said Daniel C. Ustian, Navistar chairman, president and chief executive officer.

"We were also affected by speculation surrounding our engine certification for our Class 8 engine, which is why we are working tirelessly with the U.S. EPA to get resolution." Without that certification, EPA fines cost the company $10 million in penalties in the second quarter.

Ustian declined to estimate when the EPA would rule, Bloomberg reported.

Troy Clarke, currently president of Navistar Asia Pacific, will assume responsibility for all Navistar's operations in the newly created role of President, Truck and Engine. Clarke joined Navistar in 2010 after a 35-year career at General Motors.

Jack Allen will become president of North America Truck and Parts, an expansion of his current role, and Engine Group President Eric Tech will expand his role to become president of Global Truck and Engine, responsible for all of Navistar's business operations outside of North America.

According to published reports, Dee Kapur, president of Navistar's truck group, was named vice chairman and chief product officer.

The changes will take effect July 1, following Board approval.

Navistar reported a loss of $172 million, or $2.50 per diluted share, for the second quarter ended April 30, 2012. After pre-tax adjustments to exclude net impact of pre-existing warranty charges of $104 million related to 2010 emission standard engines, asset impairment charges of $38 million, engineering integration costs of $29 million, a charge of $10 million for non-conformance penalties, and the release of an $181 million income tax valuation allowance related to Canadian deferred tax assets, Navistar's loss for the second quarter 2012 was $137 million, or a loss of $1.99 per diluted share.

The engine division recorded a loss of $108 million, compared with a year-ago profit of $2 million.

The company lowered its annual profit forecast -- the second time it's done so this year -- to a range of break even to $2 a share. The average of 17 analysts' estimates was for an annual profit of $3.79 before today, reports Bloomberg.

"Historically, the second half is stronger across our businesses," Ustian said, "and we expect to build on this with improved market share in North America, stronger global performance and further cost reductions across all operations."

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6/1/2012 Frost & Sullivan: Navistar Will Recover in Long Term

5/17/2012 Court Papers: EPA Penalties Keep Navistar in Class 8 Business

2/14/2012 Vertical Integration Yields More Profits, Navistar Executives Tell Stock Analysts