Tuesday’s stock market session on January 27, 2026, was anything but predictable, as a cascade of breaking news sent shares of major U.S. companies on a rollercoaster ride. From healthcare giants reeling under regulatory proposals to tech and manufacturing heavyweights celebrating lucrative deals, investors had plenty to chew on as the trading day unfolded.
The most dramatic swings came from the healthcare sector. According to CNBC and corroborated by Investing.com, shares of UnitedHealth Group, Humana, and CVS Health all plummeted after the Centers for Medicare & Medicaid Services (CMS) released its much-anticipated proposal for 2027 Medicare Advantage payment rates. The proposed increase? A mere 0.09%—a figure that fell far short of the 4-6% hike many on Wall Street had expected. In an instant, the mood among investors soured.
UnitedHealth Group saw its stock tumble by approximately 17.64%, while Humana’s shares took an even steeper dive, closing down about 18.91%. CVS Health wasn’t spared, with its shares sliding nearly 13% by the end of the day. These sharp declines underscored the sector’s sensitivity to government reimbursement policies—and the outsized role Medicare Advantage plays in these companies’ bottom lines.
As CNBC reported, the market’s reaction was swift and punishing. The CMS proposal, which was intended to adjust payment rates for the popular Medicare Advantage program, blindsided industry watchers. The FactSet consensus had anticipated a much more generous adjustment, and the reality of a near-flat rate sent shockwaves through the insurance sector. The Trump Administration’s stance on holding rates steady added to the uncertainty, as highlighted by the Wall Street Journal and Investing.com.
But while some were licking their wounds, others were celebrating. Corning, the renowned glass and materials manufacturer, saw its shares rally an impressive 5.9% (and as high as 16.65% by some accounts) after CEO Wendell Weeks revealed a blockbuster deal with Meta. In an exclusive interview with CNBC, Weeks confirmed that Meta had committed to spend up to $6 billion with Corning through 2030, securing fiber-optic cable for its rapidly expanding AI data centers. The deal not only buoyed Corning’s stock, but also signaled the growing arms race among tech giants to build out infrastructure for artificial intelligence.
Elsewhere, General Motors (GM) gave investors a reason to smile. The automaker’s stock jumped more than 4% after it reported fourth-quarter earnings that beat analyst expectations and issued a bullish outlook for 2026. GM sweetened the pot by announcing a 20% increase in its quarterly dividend and unveiling a $6 billion stock buyback program. According to CNBC, these moves were welcomed by shareholders eager for signs of confidence and stability in the face of ongoing industry headwinds.
Boeing, too, had reason to celebrate. The airplane maker reported fourth-quarter revenue of $23.95 billion, surpassing the $22.6 billion forecasted by analysts at LSEG. CEO Kelly Ortberg, in a memo to staff, struck an optimistic tone, stating, "There’s a lot to be optimistic about." Boeing’s shares responded by climbing 2% in the wake of the news.
American Airlines, meanwhile, projected robust growth for the coming year, forecasting a 7% to 10% increase in first-quarter revenue compared to 2025. The company also predicted an improvement in adjusted earnings per share by mid-2026, even as its fourth-quarter results fell short of expectations. Investors appeared to look past the recent miss, sending shares up nearly 3% on the day.
United Parcel Service (UPS) joined the winners’ circle after posting adjusted fourth-quarter earnings of $2.38 per share on revenues of $24.48 billion. Both figures beat analyst estimates, and the stock responded with a 3.6% gain. According to CNBC, analysts polled by LSEG had anticipated per-share earnings of $2.20 on revenues of $24.00 billion, making the results a pleasant surprise for shareholders.
Not every earnings report was met with applause, however. Nucor, the steel manufacturer, saw its shares dip more than 2% after reporting fourth-quarter adjusted earnings of $1.73 per share and revenue of $7.69 billion—both figures missing the FactSet consensus. Sanmina, an electronics manufacturing services provider, fared even worse, with its stock sliding more than 9% (and as much as 16.73% by some accounts) after revenue guidance failed to meet expectations.
In the tech sector, Salesforce made headlines after securing a massive $5.6 billion, 10-year contract with the U.S. Army. The announcement sent Salesforce shares up 2.4%, signaling continued confidence in the company’s ability to land major government deals.
Meanwhile, CoStar, a real estate marketplace and analytics company, saw its shares pop nearly 6% after hedge fund Third Point launched an activist campaign against the firm. Activist investors often seek to shake up management or strategy in hopes of unlocking shareholder value, and the market’s reaction suggested optimism about potential changes ahead.
The day’s action wasn’t limited to blue chips and household names. Across the market, notable movers included Micron Technology (+5.0%), Lam Research (+6.25%), Applied Materials (+4.87%), and Intel (+3.36%). In the mid-cap and small-cap arenas, companies like Redwire (+29.85%), Junee (+33.56%), and Richtech Robotics (+22.08%) delivered eye-catching gains, often on the back of contract wins or positive earnings surprises.
Yet, the shadow of regulatory uncertainty loomed large, particularly for healthcare stocks. The CMS proposal for Medicare Advantage rates—a seemingly arcane policy decision—proved to be the day’s most potent market mover. As the Wall Street Journal and Investing.com both emphasized, the Trump Administration’s push for flat rates caught many off guard and sparked a sector-wide selloff. The episode served as a vivid reminder of how government decisions can ripple through markets, upending expectations and fortunes in a matter of hours.
For investors, the day was a study in contrasts: soaring optimism for some, sharp disappointment for others, and a prevailing sense that in today’s market, nothing is ever set in stone. The only certainty? Volatility remains the name of the game.