Tuesday delivered the kind of market action that makes scrolling through your portfolio actually enjoyable. U.S. stocks posted solid gains across the board, with the Dow Jones Industrial Average climbing over 480 points for a 0.99% increase to 49,462.08. The NASDAQ rose 0.65% to 23,547.17, while the S&P 500 added 0.62% to reach 6,944.82.

But the real story wasn't in the indexes. It was in the individual stocks that captured investor attention, from memory chip makers riding a wave of AI-driven optimism to biotech companies delivering clinical trial results that sent shares into the stratosphere.

SanDisk Rides the Memory Wave

SanDisk Corporation (SNDK) had the kind of day that makes you wish you'd been paying attention. Shares surged 27.56% to close at $349.63, hitting an intraday high of $352 and a 52-week peak of $352. That's quite a journey from the 52-week low of $27.90. After hours, the rally continued with the stock climbing another 2.3% to $357.75.

The catalyst? Comments from Nvidia Corp. (NVDA) CEO Jensen Huang at CES 2026, where he emphasized the growing need for both memory and storage solutions. When the CEO of the company defining the AI hardware landscape speaks, people listen.

The options market certainly heard him loud and clear. Recent activity showed 110 trades with significant bullish sentiment, with 40% of those trades opened with bullish expectations. Analysts have been more cautious, with price targets ranging from $235 to $300 following SanDisk's 2025 spin-off from Western Digital. The market, at least for now, seems to think those targets might be too conservative.

Alumis Delivers Clinical Trial Gold

If SanDisk had a good day, Alumis Inc. (ALMS) had an absolutely spectacular one. Shares rocketed 95.31% to close at $16.23, hitting an intraday high of $22.30 and establishing a new 52-week high. The stock added nearly 2.6% in after-hours trading to reach $16.65, extending gains from a 52-week low of just $2.76.

The reason? Alumis reported positive topline results from its Phase 3 ONWARD1 and ONWARD2 trials of envudeucitinib in moderate-to-severe plaque psoriasis. And these weren't just positive results—they crushed expectations, meeting all primary and secondary endpoints with high statistical significance.

Here's what matters: Across both trials, 74% of patients achieved PASI 75 and 59% reached sPGA 0/1 at Week 16, with responses improving over time. The drug showed rapid separation from placebo as early as Week 4. By Week 24, approximately 65% of patients achieved PASI 90 and more than 40% hit PASI 100. Perhaps most impressively, envudeucitinib outperformed Amgen's Otezla on all PASI endpoints.

The drug was generally well tolerated through Week 24, and Alumis is planning additional data presentations with an NDA submission targeted for the second half of 2026. That's the kind of clinical readout that makes biotech investors very happy.

Micron Gets a Valuation Rethink

Micron Technology Inc. (MU) shares increased 10.02% to close at $343.43, with the stock reaching an intraday high of $344.55 and a new 52-week high of $344.55. That's a remarkable climb from the 52-week low of $61.54.

The move reflects something interesting happening in tech stocks more broadly. After months of uncertainty, tech stocks have quietly slipped back toward attractive valuations. Wedbush's Dan Ives has pointed to as much as 25% upside for the sector if a rerating unfolds, and investors appear to be taking that seriously.

Within the Nasdaq-100, several technology names are trading at low forward price-to-earnings multiples despite improving earnings visibility. That's a disconnect between fundamentals and valuation that doesn't usually last long.

Micron stands out even after rallying strongly into year-end. The stock still trades at a single-digit forward multiple of approximately 9.8 times earnings. The move suggests investors are beginning to price in an earnings reset tied to AI-driven memory demand and a recovery in pricing dynamics, rather than simply chasing momentum. When a company with Micron's position in the AI supply chain trades at less than 10 times forward earnings, people start to notice.

Ventyx Becomes an Acquisition Target

Ventyx Biosciences Inc. (VTYX) shares rose 28.52% to close at $10.05, but the real action came after the bell. The stock reached an intraday high of $25 before pulling back, ultimately shooting up nearly 62.6% to $16.34 in extended trading. The 52-week range tells the story: from a low of $0.78 to a high of $25.

The Wall Street Journal reported that Eli Lilly is in advanced talks to acquire Ventyx for more than $1 billion, citing people familiar with the matter. For Lilly, the potential deal would add Ventyx's pipeline of drugs targeting inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, along with treatments for Parkinson's disease.

It's the kind of acquisition that makes strategic sense for a pharmaceutical giant looking to bolster its portfolio in inflammation and neurodegenerative diseases. For Ventyx shareholders who bought anywhere near that 52-week low, it's been quite a ride.

Western Digital Catches the Same Wave

Western Digital Corporation (WDC) shares gained 16.77% to close at $219.38, with the stock reaching an intraday high of $221.23 and a new 52-week high of $221.23. Like SanDisk, Western Digital has come a long way from its 52-week low of $28.83.

Western Digital emerged as one of Tuesday's top gainers as memory chip stocks rallied early in 2026. The move was driven by expectations of rising memory prices amid a global supply crunch, lifting peers including SanDisk and Seagate in the process.

The rally came as investors rotated into cyclical and blue-chip names during a broader market advance. When you combine improving fundamentals in the memory market with attractive valuations and positive sector momentum, you get days like Tuesday. Memory chips might not be the most exciting product category, but the stocks sure can be when the fundamentals align.