Ford Motor Co. (F) on Tuesday said second-quarter profit more than doubled, but its shares fell as much as 4.5 percent on disappointment that gains were driven by the finance arm while its core automotive operations posted a loss.

The increased earnings, which topped Wall Street estimates, came as the No. 2 U.S. automaker's market share in the United States fell by 1.2 percentage points in the second quarter and its U.S. sales dropped by 5 percent.

"Ford's results beat expectations but the overwhelming concentration of earnings in financial services will likely give investors reasons for pause," Merrill Lynch John Casesa told clients in a note.

Ford raised its full-year earnings estimate for the third time this year, by 15 cents to $1.80 to $1.90 a share. Analysts noted that the outlook was raised solely on strong Ford Credit (search) results.

"The first read of changes to guidance suggest automotive profitability could be worse than expected this year," said UBS analyst Robert Hinchliffe.

Ford's automotive operations are key to future profitability as Ford Credit is likely to be hurt by rising interest rates.

The Dearborn, Mich.-based automaker also said it expects third-quarter results to range from break-even to a profit of 5 cents per share, below analysts' average estimate of 13 cents. Ford often tops its own estimates, however.

Ford net income rose to $1.2 billion, or 57 cents a share, from $417 million, or 22 cents a share, a year earlier.

Excluding special items such as charges from restructuring in Europe and Ballard Power Systems (search), Ford earned 61 cents per share, beating the average 49 cents per share estimate from analysts polled by Reuters Estimates.

Total revenue rose to $42.8 billion from $40.7 billion.

Ford, which has been backing away from low-margin fleet and daily-rental sales, said its automotive unit had a pretax loss of $57 million, compared with a pretax profit of $3 million a year ago. Excluding special items, the automotive unit made a pretax profit of $83 million.

Ford Credit, meanwhile, reported net income of $897 million, up sharply from $401 million a year ago.

"At some point we are going to have to see the auto profits lead the way," Hinchliffe told Reuters.

Ford said its finance arm's earnings were helped by fewer credit losses, lower interest rates and improved values for used vehicles. Higher used-car values lift margins when vehicles coming off leases are sold at auction.

Ford's European operations made a pretax profit of $211 million, excluding special items, compared with a pretax loss of $525 million a year earlier.

But Ford's Premier Automotive Group — which includes Land Rover, Volvo and Jaguar — was hit by a strong euro, model changeovers and higher operating costs, Ford Chief Financial Officer Don Leclair told reporters and analysts in a conference call. The division, which is supposed to account for a third of Ford's automotive profits by 2006, swung to a pretax loss of $362 million from a pretax profit of $166 million a year ago.

Jaguar's U.S. sales in particular were disappointing, Leclair said, adding that Ford is working to turn around the luxury-car unit.

Ford's cross-town rival General Motors Corp. (GM) is due to report second-quarter results on Wednesday.

Ford shares closed down 38 cents to $14.60, after falling to $14.30 earlier on the New York Stock Exchange.