Fund managers are stampeding into shares of U.S. long-haul trucking company Swift Transportation Co as oil prices touch five-year lows, but some analysts say a shortage of drivers may slam the brakes on the rally.

Portfolio managers from Goldman Sachs, Fidelity, and Federated Investors were among the 65 funds that added Swift shares to their portfolios over the last three months, an 80 percent jump in institutional purchases from the quarter before, according to Morningstar.

Portfolio managers have been attracted to the company, which is one of the largest in its industry and has a market value of $3.8 billion. They expect falling fuel costs and a jump in shipping volumes as a result of increased consumer spending to send Swift’s above-average margins higher.

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