Updates prices throughout

By Shashwat Chauhan and Avinash P

July 7 (Reuters) - Nasdaq futures dropped on Tuesday following declines in chip stocks as investors reassessed the sustainability of the AI-driven rally despite strong results from Samsung, while SpaceX shares dipped ahead of their Nasdaq-100 debut.

Elon Musk's SpaceX SPCX.O was set to begin trading as part of the Nasdaq-100 index .NDX on Tuesday and a wave of brokerages initiated coverage on the stock as an industry-mandated quiet period ended. Its shares fell 0.5% in premarket trading.

Chip shares led losses, with memory chipmakers Micron Technology MU.O down 5.8%, Western Digital WDC.O off 6.8% and Sandisk SNDK.O losing 6%.

Samsung Electronics' 005930.KS shares sank in South Korea despite the company reporting a 19-fold jump in second-quarter operating profit and surpassing its combined earnings over the past three years.

"The wider issue is whether this is a new chapter for investor reaction, related not to any weakness in demand or immediate profitability," said Richard Hunter, head of markets at interactive investor.

"But rather, whether the level of earnings can be maintained in order to repay the trillions of dollars which have been funneled into AI investment by the hyperscalers."

Nvidia's shares NVDA.O added to earlier losses and last fell 1.6% after Reuters reported China's startup DeepSeek is developing its own AI chip.

Chip stocks have been some of the biggest winners of the AI trade so far this year amid hopes of insatiable AI demand, though concerns of the sector being overbought and profit-taking by investors have led to some volatility lately.

Other chip-related stocks including Intel INTC.O fell 4.3%. Marvell Technology MRVL.O also eased and was down 5.1% amid sectorwide weakness.

Another test of the appetite for chip stocks looms later this week, when South Korean giant SK Hynix's 000660.KS U.S. listing begins trading on the Nasdaq.

At 06:47 a.m. ET, Dow E-minis YMcv1 rose 94 points, or 0.18%, S&P 500 E-minis EScv1 fell 12.75 points, or 0.17%, and Nasdaq 100 E-minis NQcv1 lost 292 points, or 0.98%.

Dow futures bucked the trend as software plays Microsoft MSFT.O, Salesforce CRM.N and IBM IBM.N rose. The blue-chip index crossed the 53,000-point mark on Monday for the first time ever.

The index clocked its fifth 1,000-point milestone this year as receding oil prices on the back of easing Middle East tensions have offered support lately.

Oil prices, however, rose on Tuesday following reports of attacks on vessels near the Strait of Hormuz.

Morgan Stanley said in a note dated Monday the recent weakness in U.S. semiconductor stocks is a sign that market gains are broadening, with investors likely to turn to AI hyperscalers.

Fiserv FISV.O climbed 6.1% after media reports that the payments firm had held discussions with U.S. banks including JPMorgan JPM.N and Bank of America BAC.N to sell its payments infrastructure business that handles debit card transactions.

Rivian RIVN.O dropped 8.6% after the electric-vehicle maker launched an offer to sell 75 million shares even as it forecast second-quarter revenue above analysts' estimates.

Meanwhile, U.S. Federal Reserve watchers will get another glimpse into how new Chair Kevin Warsh steers the central bank when the minutes of its last meeting are released on Wednesday, the first of his tenure.

Traders currently see at least one 25-basis-point rate hike on the cards this year, according to data compiled by LSEG.