(Reuters) - The Big Three U.S. automakers on Wednesday reported a rise in sales of pick-up trucks for the third quarter as lower interest rates boosted demand in an otherwise sluggish auto market.

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Shares of General Motors GM.N, Ford Motor F.N and Fiat Chrysler FCHA.MI were, however, trading lower, tracking a broad selloff in the market over fears of a U.S. slowdown.

While higher vehicle prices and rising interest rates earlier in the year kept car shoppers on the sidelines, recent interest rate cuts helped sales in the third quarter.

Automakers in the United States are also focusing on selling larger SUVs and trucks that are more profitable, as sedans fall out of favor.

“Gas prices and interest rates remain at historically low levels ... (and) support our industry to 17 million plus level for what is now the fifth straight year,” Mark LaNeve, Ford’s vice president of U.S. marketing, sales and service, said on a call with analysts.

There were concerns that GM’s sales could take a hit after 48,000 hourly employees at the top U.S. automaker walked out for the first time in 12 years on Sept. 16 and remain on strike.

GM did not face a severe inventory crunch in the third quarter, as most dealers showed healthy supply levels heading into October, according to an analysis by automotive shopping website CarGurus.

However, the company risks facing parts shortage that could possibly affect sales in the current quarter, likely benefiting rivals including Ford.

Sales of Silverado pick-up trucks jumped 16.6% to 155,482 vehicles, boosting GM’s total U.S. sales by 6.3% to 738,638 vehicles.

Sales of Ford’s pick-up trucks rose 5% to 240,387, their best third-quarter performance in 14 years, even as overall sales fell 4.9% to 580,251 units, hurt by lower demand for the company’s passenger cars including the Taurus sedan.

Fiat Chrysler’s sales of its Ram pick-up trucks surged 14% to 161,635, marginally lifting overall sales by 0.1% to 565,034 units.

GM’s sales fell slightly short of U.S. car shopping website Edmunds’ forecast of 748,746 vehicles, while Ford and Fiat Chrysler beat expectations. Edmunds had expected third-quarter sales for the industry to rise by 0.8% to 4.3 million vehicles, led by volume gains at GM.

Edmunds had forecast Ford’s sales at 570,179 vehicles and Fiat Chrysler’s at 558,302.

The results showed September U.S. light vehicle seasonally adjusted annualized pace was tracking 17.2 million vehicles, above consensus of 17 million, J.P. Morgan analyst Ryan Brinkman said.

Shares of GM fell 4.7% to their near four-month low of $34.41, while those of Ford slumped 5.2% to more than six-month low of $8.44. Fiat Chrysler’s U.S.-listed shares slipped 2.1% to $12.46.