Companies large and small are on alert for a wave of attacks this year from activist investors:

• 2022 saw a record number of new activist investors, and a record share of activist activity targeting giants — including Alphabet, Meta and Salesforce, Michael Flaherty writes for Axios Pro: Deals.

In a preview of this new landscape, Trian Partners last week claimed victory over Disney in a proxy fight.

• Irenic Capital's attack on News Corp last fall captured two key activist trends in a single campaign: Irenic was a first-time activist, and it targeted a large, blue-chip industry name.

🧠 What's happening: Easing volatility and low valuations are keeping activists on center stage. And a drop in M&A volume is among the drivers for big-ticket activist campaigns.

• Valuations have come down, creating opportunities.

Jim Rossman, Barclays' global head of shareholder advisory, said: "What had always held back the expansion of activism was boards who supported management teams come hell or high water. That's changing."

• "Now you've got ... stock-picking value investors who tell management teams that if you don't listen to me, we'll reach out to the concentrated owners of your stock."

Share this story ... Try Axios Pro: Deals.

Perhaps based on increased vigilance rather than fresh threats, the U.S. yesterday shot down the fourth airborne "object" in eight days.

• Defense officials said during an off-camera briefing, held during the Super Bowl, that they don't yet know if the most recent three objects were balloons, or even how they're propelled.

Why it matters: The mysterious chain of events over U.S. airspace has no peacetime precedent, the briefers said.

🔎 Between the lines: The Pentagon briefers allowed for the possibility that the objects are commercial and innocuous — they haven't recovered them yet, and just don't know.

• The N.Y. Times reports one U.S. theory: "China or Russia sent the objects to test American intelligence-gathering capabilities."

The shootdowns:

1. Two Saturdays ago, off South Carolina: The Chinese spy balloon was shot down after traversing the U.S. for most of the week.
2. Friday, off northern Alaska: An Air Force F-22 fighter shot down a "high-altitude object" that was flying at 40,000 feet and posed a threat to civilian airliners, the Pentagon said. The object — which was about the size of a small car, and bore no resemblance to the Chinese balloon — dropped onto sea ice near Deadhorse, Alaska.
3. Saturday, over northern Canada: An F-22, coordinating with Canada, used a missile to shoot down a high-altitude airborne object that NORAD had detected over Alaska late Friday. (Read the statement.)
4. Yesterday, over Lake Huron, Mich.: At the direction of President Biden, "out of an abundance of caution," an F-16 fired an AIM9x missile to "shoot down an airborne object flying at approximately 20,000 feet altitude in U.S. airspace." (Read the statement.)

🛸 Could these be aliens? At the briefing, Air Force Gen. Glen VanHerck, head of NORAD and the U.S. Northern Command, got the internet excited by saying when asked whether he ruled out aliens or extraterrestrials:

• "I'll let the intel community and the counterintelligence community figure that out. I haven't ruled out anything."

🥊 Reality check: The N.Y. Times reports that "national security officials discounted any thoughts that what the Air Force shot out of the sky represented any sort of alien visitors."

• "No one, one senior official said, thinks these things are anything other than devices fashioned here on Earth."

Audio of the UFO answer ... Get the latest.

The GOP's House campaign arm is eyeing former Speaker Pelosi's decision to stay in Congress as messaging gold, Axios' Andrew Solender has learned.

• Why it matters: Generations of Republican candidates and consultants have made Pelosi a favorite foil. They're not letting go, despite Dems' relatively seamless transition to a fresh leadership team.

The messaging strategy involves targeting House Democratic Leader Hakeem Jeffries (D-N.Y.) as being inexperienced in the top job.

• In a break with most modern predecessors, Pelosi opted to remain as a representative from San Francisco. Her colleagues voted to give her the honorary title "Speaker Emerita."

Jack Pandol, communications director for the National Republican Congressional Committee (NRCC), told Axios: "As Jeffries ... forces his vulnerable members to unquestionably defend Joe Biden from accountability, it's not clear Pelosi's training wheels have been effective."

👀 What caught our eye: Pelosi, who has led her caucus since 2003 and is known as a fundraising powerhouse thanks to her connections to wealthy California donors, has been introducing Jeffries to her network as he steps into his new role, according to Punchbowl News.

• Share this story.

Celebrities and social media influencers are promoting the off-label use of diabetes drugs for weight loss, prompting a spike in prescriptions and concerns about cost and possible shortages, Tina Reed writes for Axios Vitals.

• More than 5 million prescriptions were written for Novo Nordisk's Ozempic or Eli Lilly's Mounjaro for weight management in 2022, up from about 230,000 in 2019, per Komodo Health.

How it works: The drugs are part of a relatively new class that mimic a hormone in the body and regulate appetite and blood sugar levels.

• Ozempic and Mounjaro have been approved by the FDA for treating diabetes while drugs like Novo Nordisk's Wegovy and Saxenda have been approved for treating obesity.

Between the lines: There are concerns about who should be on these drugs, which don't work for everyone and can cost $1,400 a month out-of-pocket if insurance doesn't pay.

• Share this story.

Axios will host our second annual What's Next Summit on March 29 in Washington.

• The What's Next Summit is our crystal ball, illuminating innovations, trends and people breaking boundaries and shaping our world.

During the daylong event, Axios journalists will lead interviews with newsmakers on AI, the future of work, space travel and more.

• Speakers include United Airlines CEO Scott Kirby, Vimeo CEO Anjali Sud, music producer Timbaland and more.

Click here to register.

The average U.S. tariff rate on women's underwear is 15%, compared to 11.5% for men's underwear, Axios' Emily Peck writes from an analysis by a former U.S. trade official, highlighted by a Washington Post opinion column.

• "Worst Valentine's Day surprise ever," Ed Gresser writes in the Progressive Policy Institute report.

Tariffs are the taxes the federal government puts on imported goods. Sometimes administrations monkey around with them to help U.S. manufacturers, or for other international relations-y reasons.

• But these underpants tariffs aren't about boosting domestic panty producers. In fact, 98% of clothing in the U.S. is imported.

🧮 By the numbers: Because the tariff rate is higher and because women buy more underwear, about three-quarters of the $1.54 billion the U.S. collected in underwear tariffs last year was from women's undergarments, Gresser found.

• "[O]n average the tariff system appears to add about $1.10 to the cost of each women's underwear item, and 75 cents to men's."

🥊 Reality check: It's unlikely the panty gender gap is intentionally discriminatory. "The patterns seem to date back to lobbying from earlier eras," The Post's Catherine Rampell writes.

• "In the garment industry, U.S. manufacturers might have felt most threatened by foreign competition on more labor-intensive products, which were disproportionately women's products."

Rihanna shocked fans by revealing her pregnancy during the Apple Music Super Bowl halftime show, Axios' Maxwell Millington writes.

• The seven-time Grammy winner's representatives confirmed that she's expecting her second child.

Why it matters: The 34-year-old became the show's first pregnant headliner. She's also the halftime show's first female billionaire performer.

• It was Rihanna's first solo performance in seven years.

Rihanna hinted that she was "thinking of bringing someone" on stage in an interview before the show.

• She gave birth to a son with rapper A$AP Rocky last May.

Watch the video ... More photos.

Kansas City Chiefs QB Patrick Mahomes — playing through an ankle injury — became the first player in NFL history with multiple championships and multiple MVPs in his first six seasons, Axios Sports co-author Jeff Tracy writes.

• The Chiefs are world champs yet again, beating the Eagles 38-35 in the third-highest-scoring Super Bowl ever.

Wild stat: Teams leading by double digits at halftime of the Super Bowl were 26-1 before yesterday. Now, they're 26-2.

More photos ... Get Axios Sports.