Wall Street set for lower open on tariff uncertainty; data in focus

• Futures down: Dow 0.8%, S&P 500 1.1%, Nasdaq 1.4%
• PepsiCo gains after report says Elliott plans activist campaign
• Gold miners gain as bullion prices hit record high

Sept 2 (Reuters) - U.S. stock index futures pointed to a lower open on Tuesday, as investors returning from a long holiday weekend worried about the legality of President Donald Trump's tariffs and awaited crucial economic reports.

A divided U.S. appeals court ruled on Friday that most of Trump's tariffs are illegal , undercutting the U.S. president's use of these levies as a key international economic policy tool.

However, the court allowed for the tariffs to be in place until October 14 to give the administration a chance to file an appeal with the Supreme Court.

Yields on longer-dated U.S. Treasuries rose on Tuesday, with those on the 10-year US10YT=RR and 30-year US30YT=RR notes at their highest levels in more than a month, pressuring equities.

The CBOE Market Volatility index .VIX also touched its highest mark in more than three weeks and was last up 2.77 points at 18.89.

"If the Supreme Court rules the tariffs to be illegal, the government has to pay all that money back ... if there's more debt, yields will rise higher, which means more trouble for the market," said Robert Pavlik, senior portfolio manager at Dakota Wealth.

At 8:46 a.m. ET, Dow E-minis YMcv1 were down 396 points, or 0.87%, S&P 500 E-minis EScv1 were down 71.5 points, or 1.1% and Nasdaq 100 E-minis NQcv1 were down 331.5 points, or 1.41%.

Meanwhile, caution also prevailed ahead of the August nonfarm payrolls report, due on Friday, which will follow a monthly private payrolls reading and job openings figures.

Markets are pricing in about a 92% chance of a 25-basis-point cut in interest rates at the Fed's meeting later this month, according to the CME Group's FedWatch tool.

Investors' dovish tilt came after July's weak job report, with Fed Chair Jerome Powell acknowledging the growing risks to the labor market at the Jackson Hole symposium, helping the S&P 500 and the Dow log their fourth consecutive month of gains in August.

The Nasdaq logged its fifth straight monthly gain last month.

Meanwhile, hedge funds remained hesitant about buying U.S. stocks at the outset of seasonally dour September, according to Goldman Sachs data up to August 25.

The benchmark S&P 500 has lost 1.5% on average in September - its worst month - since 2000, according to data compiled by LSEG. DataTrek Research said it is the only month since 1958 where the index's mean returns are negative.

On Tuesday, U.S. manufacturing activity data for August is due after markets open.

A White House official said that Trump would make an announcement related to the U.S. defense department later in the day.

In stocks, gold miners gained in premarket trading after bullion prices hit a record high. U.S.-listed shares of Harmony Gold HMY.N rose 6.2%, Kinross Gold KGC.N gained 2.4% and Newmont NEM.N added 1.4%.

PepsiCo PEP.O shares gained 4.8% after a report by the Wall Street Journal said Elliott Management had taken a $4 billion stake in the beverages giant and was planning an activist campaign.

Quarterly earnings from retailers this week will also be on the radar.