(Bloomberg) — Self-driving technology companies are the latest automotive stocks to become an obsession of retail traders, with firms like Aurora Innovation Inc. surging Friday on high volume.

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Aurora, which went public via special purpose acquisition company earlier this month, jumped as much as 57% Friday after the stock was widely cited on social media platforms Twitter and StockTwits. A report that iPhone-maker Apple Inc. is pushing to develop a car with a full self-driving system also helped attract investors’ attention to the group.

Aurora later pared some of the gains to close up 51% in New York. The stock is now up 71% this week.

While Aurora’s advance was the most stark, other stocks also rose sharply. TuSimple Holdings Inc., which makes self-driving technology for heavy-duty and semi trucks, gained as much as 7.9% before closing up 5.9%. The optimism also spread to makers of lidar sensors used in driver-assistance systems, sending shares of Innoviz Technologies Ltd., Aeva Technologies Inc. and Velodyne Lidar Inc. higher.

The moves are reminiscent of gains in electric-vehicle stocks earlier this week, when Rivian Automotive Inc. and Lucid Group Inc. both posted double-digit jumps and surpassed some of their more established peers in market value.

Over 36 million Aurora shares changed hands on Friday, significantly higher than the volume of Tesla Inc. An unusually heavy trading volume typically suggests high interest from retail traders.

(Updates stock moves throughout.)

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