A Chinese A.I. Company Rattled the Tech World

A month ago, almost no one in the U.S. had heard of the Chinese artificial intelligence start-up DeepSeek. Today, its reported breakthroughs prompted the erasure of hundreds of billions of dollars in market value from some of the world’s biggest companies.

Last week, DeepSeek explained how its new A.I. system could match the capabilities of cutting-edge chatbots from Google and OpenAI at a fraction of the cost. That revelation forced many investors to reassess their sky-high valuations of American tech giants.

The S&P 500 fell 1.5 percent, the Nasdaq dropped 3 percent and Nvidia, the chipmaker hailed as an A.I. sensation, dropped about 17 percent and lost roughly $600 billion in market value.

Jason Karaian, our deputy Business editor, said that analysts considered DeepSeek’s emergence to be a “slap in the face” for investors who believed the A.I. race had already picked its winners.

In a clash with Colombia, Trump showed his use of U.S. power

President Trump did not host any Situation Room meetings before threatening yesterday to impose steep tariffs on Colombia, a top U.S. ally in Latin America. Instead, he used his own social media network and his willingness to wield the American economy as a weapon in an effort to persuade Colombia’s president to accept military deportation flights.

It worked: President Gustavo Petro backed down, and Trump emerged with real evidence that his tariff threats could help him achieve his political goals.

There is little mystery about some of his next targets, my colleague David Sanger writes: Denmark, whose prime minister told Trump weeks ago that Greenland was not for sale, and Panama, where Secretary of State Marco Rubio is supposed to land in a few days to demand that it return control of the Panama Canal to the U.S. Both countries recently scrambled to find lobbyists to help them navigate the Trump administration.

In other politics news:

Auschwitz ceremonies were held with the far right rising

Dozens of world leaders joined a group of fewer than 50 Nazi death camp survivors in Poland today to commemorate the 80th anniversary of the liberation of Auschwitz, where more than 1.1 million people, mostly Jews, were murdered.

The remembrance comes as Germany and the rest of Europe experience a rise in hard-right politics that is widely viewed as an echo of the nationalism that brought Hitler to power in the 1930s. Over the weekend, Elon Musk told Germany’s rising far-right party, the Alternative for Germany (AfD), that the country had “too much of a focus on past guilt.”

Bird flu has entered a new phase

“It’s time to take the bird flu seriously,” our science reporter Apoorva Mandavilli said.

A pandemic is not inevitable, scientists say. But a series of developments over the past few weeks, including the first U.S. death from the virus and cattle herds that have shown signs of reinfection, indicated that the possibility was no longer remote. Here’s what to know.

A Paris debut with standout evening wear

The stakes were high this weekend for the designer Peter Copping. He was making his debut for Lanvin, the storied fashion house that had drifted into irrelevance in recent years.

“The result,” our critic Vanessa Friedman wrote, “had a no-nonsense power.” She was particularly impressed by a pair of gold and black evening looks. “If someone doesn’t wear them to at least one award show this season, the stylist community is not doing its job,” Vanessa said.

Hermès: Véronique Nichanian, the brand’s men’s creative director, has been at her post for 35 years. But her new collection exhibits the ingenuity of a fresh hire looking to make her mark.

Dry January is almost over. Now what?

Many people who take part in Dry January, the popular monthlong sobriety challenge, report benefits by the end of the month. But then Feb. 1 comes around and a new obstacle arises.

Should you try to stay sober for as long as possible? Return to old habits? Something in between? We asked experts for tips. Even asking those questions, they said, can help lead to healthier choices.

It’s dumpling week

There is never a bad time to eat a pocket of dough stuffed with something delicious. But this week, around Lunar New Year, dumplings take on extra meaning: For some, they symbolize wealth and prosperity for the year ahead.

To celebrate the occasion, five Times Cooking writers shared the dumplings they love most, with recipes and videos for how to make them.

Have a flavor-filled evening.

Thanks for reading. I’ll be back tomorrow. — Matthew

Sean Kawasaki-Culligan was our photo editor today.

We welcome your feedback. Write to us at evening@nytimes.com.