Shooting of MIT professor Nuno Loureiro has police searching for a suspect

BROOKLINE, Mass. (AP) — Police intensified their search Wednesday for a suspect in the killing of professor Nuno F.G. Loureiro at the Massachusetts Institute of Technology, two days after he was shot to death at his home outside Boston.

Loureiro, a 47-year-old physicist and fusion scientist, was killed Monday night at his apartment in Brookline, Massachusetts. He died at a local hospital on Tuesday, the Norfolk District Attorney’s Office said in a statement.

The prosecutor’s office said the homicide investigation was “active and ongoing” as of early afternoon Wednesday and had no update — earlier they had said no suspects were in custody.

The investigation into the MIT professor's killing comes as Brown University, another prestigious institution just 50 miles (80 kilometers) away in Providence, Rhode Island, is reeling from an unsolved shooting that killed two students and wounded nine others Saturday. Investigators provided no indication Tuesday that they were any closer to zeroing in on the gunman's identity.

The FBI on Tuesday said it knew of no connection between the crimes.

Dozens of people gathered outside Louriero’s building Tuesday night, many with candles in hand, to honor the professor’s life and support his family. Neighbors received paper notices attached to their doors with tape to place candles in their windows in Louriero’s honor. Some people cried and held each other but most attendees were silent, their breath visible in the bracing cold. A few children rode scooters from their nearby homes to the gathering.

Loureiro, who joined MIT in 2016, was named last year to lead MIT’s Plasma Science and Fusion Center, where he worked to advance clean energy technology and other research. The center, one of the school's largest labs, had more than 250 people working across seven buildings when he took the helm.

Loureiro, who was married, grew up in Viseu in central Portugal and studied in Lisbon before earning a doctorate in London, according to MIT. He was a researcher at an institute for nuclear fusion in Lisbon before joining MIT, the university said.

“He shone a bright light as a mentor, friend, teacher, colleague and leader, and was universally admired for his articulate, compassionate manner,” Dennis Whyte, an engineering professor who previously led MIT’s Plasma Science and Fusion Center, told a campus publication.

The president of MIT, Sally Kornbluth, said in a statement that the killing was a “shocking loss.” The office of Portuguese President Marcelo Rebelo de Sousa also put out a condolence statement calling Loureiro’s death “an irreparable loss for science and for all those with whom he worked and lived.”

A 22-year-old student at Boston University who lives near Loureiro's apartment in Brookline told The Boston Globe she heard three loud noises Monday evening and feared it was gunfire. “I had never heard anything so loud, so I assumed they were gunshots,” Liv Schachner was quoted as saying. “It’s difficult to grasp. It just seems like it keeps happening.”

Loureiro had said he hoped his work would shape the future.

“It’s not hyperbole to say MIT is where you go to find solutions to humanity’s biggest problems,” Loureiro said when he was named to lead the plasma science lab last year. “Fusion energy will change the course of human history.”

AP writers Mark Scolforo in Harrisburg, Pennsylvania, and Leah Willingham, contributed.

A notice encouraging neighbors of Massachusetts Institute of Technology professor Nuno F.G. Loureiro to display candles in their windows to honor his life is taped to an apartment door in Brookline, Mass., Tuesday, Dec. 16, 2025. (AP Photo/Leah Willingham)

A crowd of people holding candles gather outside the home of Massachusetts Institute of Technology professor Nuno F.G. Loureiro in Brookline, Mass., Tuesday, Dec. 16, 2025. (AP Photo/Leah Willingham)

FILE - Students walk past the "Great Dome" atop Building 10 on the Massachusetts Institute of Technology campus in Cambridge, Mass., April 3, 2017. (AP Photo/Charles Krupa, File)

A crowd of people holding candles gather outside the home of Massachusetts Institute of Technology professor Nuno F.G. Loureiro in Brookline, Mass., Tuesday, Dec. 16, 2025. (AP Photo/Leah Willingham)

NEW YORK (AP) — More drops for AI stocks are dragging the U.S. market lower Wednesday, and Wall Street is heading toward a fourth straight loss.

The S&P 500 fell 0.8% in afternoon trading, though it's still not far from its all-time high set last week. The Dow Jones Industrial Average was down 128 points, or 0.3%, as of 1:14 p.m. Eastern time, and the Nasdaq composite was 1.2% lower.

The majority of stocks within the S&P 500 were rising, but they're getting drowned out by drops from the artificial-intelligence industry.

Questions continue to dog the former superstars about whether their yearslong dominance of Wall Street meant their prices shot too high, as well as whether all the investment in AI will produce enough profit and productivity to prove worth the cost. Worries are also rising about the debt that some companies are taking on to pay for it all.

Broadcom dropped 5.4%, Oracle fell 4.6% and CoreWeave sank 4.9%. Nvidia, the chip company that’s become Wall Street’s most influential stock because of its tremendous size, fell 3% and was the heaviest weight on the S&P 500.

Only 17% of respondents in a survey of relatively big businesses by UBS said they're in production at scale with their AI projects. That could be “a reminder for tech investors to remain sober about the likely 2026 revenue growth uplift from AI products,” according to UBS analysts, though the rate continues to rise.

Also on the losing end of Wall Street was Lennar, which sank 4.9% following a mixed profit report. The homebuilder delivered a weaker profit for the latest quarter than analysts expected, though its revenue topped expectations.

Executive Chairman Stuart Miller said that conditions remain challenging, with customers feeling less confident while looking for discounts and more affordable options. As a result, the company gave limited forecasts for its upcoming financial performance.

Progressive, meanwhile, fell 2.2% after the insurer based in Mayfield Village, Ohio, said that its net income for November fell 5% from its year-ago level.

On the winning side of Wall Street were oil companies, after President Donald Trump ordered a blockade of all “sanctioned oil tankers” into Venezuela. It’s Trump’s latest escalation in pressure on Venezuela, which may be sitting on more oil than any other country.

That sent the price of a barrel of benchmark U.S. crude higher by 1.6% to $56.03, just a day after it sank to its lowest level since 2021. Brent crude, the international standard, climbed 1.7% to $59.90 per barrel.

That in turn helped ConocoPhillips rise 3.5% and cut into its loss for the year so far, which came into the day at 8.5%. Devon Energy rallied 3.6%, and Halliburton added 1%. Oil prices had dropped through most of this year on expectations that companies are pumping more than enough crude to meet the world’s demand.

Netflix climbed 1% after Warner Bros. Discovery’s board said it still recommends shareholders approve a buyout offer for its Warner Bros. business from the streaming giant, rather than a competing hostile bid from Paramount Skydance for the entire company.

Warner Bros. Discovery slipped 2.1%, while Paramount Skydance fell 3.2%.

In the bond market, Treasury yields held relatively steady ahead of a report coming on Thursday that will show how bad inflation has been for U.S. consumers.

The yield on the 10-year Treasury held at 4.15%, where it was late Tuesday.

In stock markets abroad, indexes were mixed in Europe following a stronger finish in Asia.

South Korea’s Kospi leaped 1.4% for one of the world’s bigger gains and shaved its loss for the week so far down to 2.7%.

AP Business Writer Elaine Kurtenbach contributed.

Dilip Patel, right, and Bobby Charmak, left, work on the floor at the New York Stock Exchange in New York, Wednesday, Dec. 10, 2025. (AP Photo/Seth Wenig)

Traders work on the floor at the New York Stock Exchange in New York, Wednesday, Dec. 10, 2025. (AP Photo/Seth Wenig)

Currency traders work near a screen showing the Korea Composite Stock Price Index (KOSPI), left, at the foreign exchange dealing room of the Hana Bank headquarters, in Seoul, South Korea, Wednesday, Dec. 17, 2025. (AP Photo/Ahn Young-joon)

A currency trader watches monitors near a screen showing the Korea Composite Stock Price Index (KOSPI) at the foreign exchange dealing room of the Hana Bank headquarters, in Seoul, South Korea, Wednesday, Dec. 17, 2025. (AP Photo/Ahn Young-joon)

A currency trader stands near a screen showing the Korea Composite Stock Price Index (KOSPI), top left, and the foreign exchange rate between U.S. dollar and South Korean won at the foreign exchange dealing room of the Hana Bank headquarters, in Seoul, South Korea, Wednesday, Dec. 17, 2025. (AP Photo/Ahn Young-joon)