Apple, Google and other Nasdaq Stocks Swing Wildly in After-Hours Trading

The prices of shares in some of the world’s biggest companies seemed to alternately plummet or soar in after-hours trading on Nasdaq Inc.’s flagship exchange.

The likes ofand Microsoft Corp.’s shares appeared to fall by more than 50 percent, while’s stock was at one stage trading 348 percent higher, data from post-market trading on the Nasdaq Stock Market showed on Monday. That gave the iPhone maker a theoretical market capitalization of $3.4 trillion, compared to the $751 billion at which it was valued when trading closed on Friday.

The swings came on a day that the U.S. stock market closed early at 1 p.m., on the eve of the July 4 holiday. In another unusual detail, pricing data showed more than a dozen securities including Apple, Microsoft and Nasdaq’s own company stock at the same price, $123.47. It wasn’t immediately clear if shares changed hands at those prices.

The apparent swings triggered trading halts in some securities, according to automatically generated messages. The halts are a mechanism exchanges use to limit the impact of particularly volatile sessions. A system status alert on Nasdaq’ssaid that systems were operating normally at 8:23 p.m. ET. After-market hours on Nasdaq typically last from 4 p.m. to 8:00 p.m.

Will Briganti, a spokesman for Nasdaq, was unable to immediately comment on the situation.