April 24 (Reuters) - Wall Street futures were mixed on Friday, with markets heading toward the end of a week overshadowed by the U.S.-Iran stalemate that extinguished hopes of a swift end to the war.

After widespread speculation around a second round of negotiations between Washington and Tehran, no talks took place, and there is still no clarity on when they might.

U.S. President Donald Trump unilaterally extended the ceasefire with Iran, but maintained the naval blockade of Iranian ports. Iran also seized ships attempting to pass through the Strait of Hormuz.

Some investor fatigue may also be setting in. Israel and Lebanon extended their ceasefire for three weeks at a meeting brokered by Trump, but investors are holding out for firmer evidence of lasting progress.

Strong earnings from a series of corporations offered some respite. Yet with the results taking into account just one month of the war disruption, some investors have questioned how reliable they are as a guide to what lies ahead.

At 5:19 a.m. ET, Dow E-minis fell 177 points, or 0.36%, S&P 500 E-minis were flat, and Nasdaq 100 E-minis advanced 162.25 points, or 0.60%.

Oil prices remain the biggest source of uncertainty, as Brent crude futures are still around 47% above pre-war levels because of disruption in the crucial Strait of Hormuz shipping route.

Still, some see the pullback as a buying opportunity, arguing that valuations have become more compelling.

The S&P 500 and the Nasdaq Composite have hit record highs in recent days on the belief that the economic fundamentals remain solid despite the war.

"Strong market entry points are rarely found during moments of comfort or clarity. Instead, the most attractive buying opportunities are typically associated with periods of market stress," said Jeff Schulze, head of economic and market strategy at ClearBridge Investments.

Stocks under the spotlight in the premarket session included Intel, which jumped 23.3% after forecasting second-quarter revenue above estimates. Rival AMD rose 7.3%.

Online education platform Coursera fell 10.2% after its first-quarter results.

DeepSeek, the Chinese artificial intelligence startup whose low-cost model stunned the world last year, launched a preview of its highly awaited new model adapted for Huawei chip technology,

But the U.S. stocks battered by the model last year appeared to be holding up relatively well. ChatGPT-backer Microsoft was up 0.7%, and chip designer Marvell Technology rose 3.5%.

(Reporting by Niket Nishant in Bengaluru; Editing by Devika Syamnath)