Tech and Earnings Drive Market Rally; Key After Market Movers Reshape Portfolio Landscape

U.S. stock markets delivered a mixed performance session, with technology stocks leading the charge and earnings reports continuing to dominate the narrative. The S&P 500 climbed 0.47%, the Nasdaq 100 surged 0.87%, while the Dow Jones Industrials retreated 0.84%. Semiconductor companies and AI-related infrastructure stocks emerged as the most significant after market movers, with chip manufacturers recording impressive gains on the back of strong fourth-quarter earnings and major capital investment announcements.

Chipmakers Dominate as AI Infrastructure Becomes Major After Market Mover

The semiconductor sector proved to be the session’s biggest winner, with after market movers in the chip space delivering substantial returns. Seagate Technology jumped more than 6% to lead the Nasdaq 100, while Lam Research and Western Digital both climbed over 5%. Micron Technology surged 4% following its announcement of a $24 billion investment in Singapore to expand memory-chip production capacity. Applied Materials, KLA Corp, and ASML Holding all advanced more than 3%, demonstrating broad-based strength across the semiconductor supply chain.

The rally was fueled by recognition that AI infrastructure buildout requires significant capital spending on memory chips and related semiconductor equipment. Nvidia, Broadcom, and Microchip Technology posted gains exceeding 1%, while Intel climbed over 3%, benefiting from the broader semiconductor momentum. This collective strength among chip stocks served as the primary propeller for the overall market rally.

Healthcare Insurance Stocks Collapse: Biggest After Market Mover on Downside

In stark contrast to the technology strength, health insurance stocks delivered the session’s most dramatic after market movers on the downside. UnitedHealth Group plummeted 19% to rank among the S&P 500’s worst performers after forecasting a 2026 revenue decline—the first annual contraction in more than three decades. The weakness was triggered by the U.S. government’s proposal to hold Medicare Advantage plan payment rates flat, squeezing margins for insurers.

Humana dropped 19% in tandem with UnitedHealth, while Alignment Healthcare fell 15%. Additional pressure came from Elevance Health, CVS Health, and Centene, all declining more than 11%. Molina Healthcare fared slightly better with a 5% decline. These after market movers in healthcare illustrated investor concern over policy headwinds facing the entire medical insurance industry.

Broad Market Drivers: Political Risk and Economic Uncertainty

Beyond sector-specific dynamics, several macro factors influenced after market movers across the board. President Trump’s renewed tariff threats targeting Canadian imports created uncertainty, while concerns about a potential partial government shutdown weighed on sentiment. The possibility of ICE funding-related budget standoff threatened to disrupt government operations, adding to volatility.

Economic data painted a more cautious picture. The Conference Board’s consumer confidence index unexpectedly fell to an 11.5-year low, though the broader market absorbed this disappointment. Existing home prices rose 1.39% year-over-year, beating expectations of 1.20%. The Richmond Fed manufacturing survey weakened to -6, slightly softer than anticipated.

Standout Gainers and Decliners: After Market Movers in Detail

Beyond the semiconductor and healthcare sectors, several individual stocks emerged as notable after market movers worthy of portfolio attention. Corning rocketed 16% higher after announcing a multiyear $6 billion partnership with Meta Platforms to supply optical fiber and connectivity infrastructure for data centers. Redwire Corporation surged 26% following a missile defense contract award.

HCA Healthcare climbed 11% on Q4 earnings of $1.88 billion, topping consensus expectations of $1.73 billion. General Motors advanced 9% after delivering Q4 adjusted earnings per share of $2.51, exceeding the $2.28 forecast, and guiding full-year adjusted EPS to $11.00-$13.00. United Parcel Service gained 2% on Q4 revenue of $24.50 billion, beating estimates of $23.99 billion. RTX Corporation posted a 1% gain following Q4 adjusted sales of $24.24 billion, significantly above consensus.

On the downside, Agilysys tumbled 20% after reporting Q3 adjusted EPS of $0.42 versus the expected $0.46. Sanmina fell 17% due to Q2 revenue guidance of $3.1-$3.4 billion, trailing the $3.51 billion consensus. Roper Technologies became the Nasdaq 100’s worst after market mover, falling 14%, after guiding 2026 adjusted EPS to $21.30-$21.55, below the $21.62 consensus. Applied Industrial Technologies declined 8% on Q2 net sales of $1.16 billion versus the expected $1.17 billion.

Earnings Season Acceleration: What’s Expected This Week

The fourth-quarter earnings season gained momentum, with 102 S&P 500 companies scheduled to report results during the week. Year-to-date, 81% of the 83 companies that reported beat expectations, establishing a strong track record. According to Bloomberg Intelligence, S&P 500 earnings are projected to expand 8.4% in the quarter, with non-Magnificent Seven companies expected to grow 4.6%, demonstrating broad-based earnings improvement.

Upcoming after market movers will likely include major financial institutions, industrial giants, and technology names continuing their earnings reveals. Market participants will closely monitor forward guidance, particularly regarding tariff impacts and consumer spending trajectories. The Federal Reserve’s policy decision on Wednesday will also command attention, with the FOMC expected to maintain the fed funds target range at 3.50%-3.75%.