President Trump has made a habit of showing up to marquee sporting events in his second term — and a pattern has emerged that fans and critics have taken to calling the “Trump curse”: The teams he roots for keep losing.

The narrative gained fresh momentum Monday night when the New York Knicks, riding a 13-game postseason winning streak — the second-longest in NBA playoff history — fell to the San Antonio Spurs 115-111 in Game 3 of the NBA Finals at Madison Square Garden. Mr. Trump, watching from team owner James Dolan’s private suite, became the first sitting president to attend an NBA Finals game.

The loss snapped a 46-day run of dominance and handed the Knicks their first defeat of the series after winning the first two games on the road in San Antonio.

Fans were quick to assign blame. “KNICKS LOST WITH TRUMP IN THE BUILDING. THE CURSE IS REAL,” one widely shared post on X read. Others catalogued the president’s track record at high-profile sporting events, noting that three teams Mr. Trump publicly backed have now lost while he watched in person.

Even ESPN personality Stephen A. Smith, speaking before tip-off Monday, jokingly pledged to hold Mr. Trump personally responsible if New York lost. The team duly obliged.

California Gov. Gavin Newsom piled on, reposting a social media message that read: “The Knicks’ 13-game winning streak comes to an end after President Trump attends Game 3 of the NBA Finals,” while attaching a screenshot of an old White House post boasting of “the Trump effect.”

The Game 3 result was the latest entry in a losing streak tied to Mr. Trump’s attendance. At Super Bowl LIX in New Orleans on Feb. 9, 2025, Mr. Trump — the first sitting president to attend a Super Bowl in person — publicly predicted a Kansas City Chiefs victory. The Philadelphia Eagles won 40-22. At the College Football Playoff National Championship on Jan. 19, 2026, Mr. Trump watched from a suite at Hard Rock Stadium in Miami alongside Secretary of State Marco Rubio as the Miami Hurricanes fell to the Indiana Hoosiers 27-21.

In all three cases, Mr. Trump had publicly or visibly aligned himself with the losing side.

The reaction on social media drew comparisons to famous sports curses of the past — the Curse of the Bambino, the Curse of the Billy Goat — with some users dubbing Mr. Trump’s presence the new “Madden curse.”

Mr. Trump’s Game 3 attendance also drew complaints from Knicks fans and New Yorkers before a single shot was taken. Security protocols required several blocks around Madison Square Garden to be closed to most pedestrian and vehicular traffic, a strict no-bag policy was enforced, and fans were advised to arrive at least two hours early. A pregame watch party that had been organized outside MSG for previous games was canceled due to the Secret Service’s security perimeter.

The president was greeted with audible boos both inside the arena and outside when shown on the Jumbotron during the national anthem. Mr. Trump has been deeply unpopular in New York City, where Ms. Harris received roughly 68% of the vote to Mr. Trump’s 30% in the 2024 presidential election.

The Knicks still lead the series 2-1. Game 4 is scheduled for Wednesday night at Madison Square Garden.