Marvell Technology was up almost 9% in premarket trading on Monday after it was announced that the AI chipmaker would be joining the benchmark S&P 500 index. The semiconductor company, which trades on the Nasdaq , will join the broad-market index on June 22 and will sit alongside the 500 leading companies in the U.S., S&P Global said in a press release on Friday . Marvell was last seen up 8.8% in premarket trading and is up 210% year-to-date. Electronic manufacturing company Flex is also on the