Pony AI Inc (PONY) experienced a dramatic reversal in its stock price during Tuesday's trading session, ending with a 5.03% plunge in after-hours trading despite a remarkable 42% intraday surge. The volatility came in the wake of a significant announcement regarding a strategic partnership with Uber Technologies (UBER) to deploy Pony AI's robotaxis on the Uber platform.

The day began on a high note for Pony AI, with shares jumping 7% in early trading following the partnership news. Investor enthusiasm drove the stock to an impressive 42% gain during regular trading hours, with trading volume soaring to more than 44 million shares, dwarfing the daily average of about 5.53 million. The partnership, set to launch initially in a key Middle Eastern market later this year, was seen as a potential game-changer for Pony AI's autonomous mobility technology.

However, the tide turned in after-hours trading, with Pony AI's stock plummeting 5.03%. This sharp reversal suggests a classic "sell the news" scenario, where investors who had benefited from the substantial intraday gains decided to lock in their profits. The sudden drop underscores the speculative nature of the autonomous vehicle sector and highlights the market's sometimes counterintuitive reactions to seemingly positive developments. As Pony AI moves forward with its Uber partnership, investors will be closely watching to see how this collaboration translates into long-term value for the company.