The U.S. stock market saw some dramatic moves past week with five stocks posting the largest weekly gains and drops (Mon-Fri Oct 27 -Oct 31, 2025). For each, we highlight the drivers of the move and year-to-date (YTD) performance.

To track momentum in real time, you can use FMP's Top Traded Stocks API to see the most actively traded names.

Top 5 Weekly Gainers/Losers

Amazon (AMZN) — Top Gainer (~+7.62% this week)

Shares rallied after a blockbuster Q3: AWS grew 20% YoY to $33B, its fastest pace since 2022, and management leaned into heavier 2025 capex tied to AI infrastructure. The beat and cloud re-acceleration pushed AMZN to fresh highs into month-end.

First Solar (FSLR) — Gainer (+9.93% this week)

FSLR topped Q3 sales estimates and announced a new 3.7-GW U.S. plant, igniting a ~14% surge Friday that cemented strong weekly gains. The expansion helps onshore finishing of Series 6 modules and bolster domestic supply chains.

Western Digital (WDC) — Gainer (+17.42% this week)

WDC posted Q1 FY26 revenue +27% YoY and guided Q2 above estimates as AI-driven nearline HDD demand tightened supply and lifted margins, sending shares to record highs. Management also highlighted multi-year purchase commitments from top customers.

Chipotle (CMG) — ~-23% this week

The stock slid after a third cut to its 2025 sales outlook, with tariffs and inflation squeezing margins and signs of consumer pullback. Thursday's downgrade sparked ~19% in one session, compounding the weekly drop.

Dexcom (DXCM) — ~-17% this week

DXCM fell as executives signaled 2026 growth could undershoot Street despite a solid Q3 and raised 2025 sales guidance. Sentiment was further hit by the FDA's recent correction notice for G7/ONE+ apps over missed alerts.

Track Market Liquidity in Real Time with FMP's Top Traded Stocks API

The Top Traded Stocks API shows which tickers are commanding the most attention right now—a handy complement to weekly performance:

• Most Active Lists: Instantly see the highest-volume stocks across major U.S. exchanges (or filter by NASDAQ/NYSE).
• Real-Time Volume + Price Metrics: Monitor volume, price change, and % change to gauge momentum and liquidity.
• Company Snapshot: Pull names, symbols, and trading volume for quick context.

Example use case: A day trader scans NASDAQ via the Top Traded Stocks API and spots iSun (ISUN) printing unusually high volume. With real-time volume and price-change data in hand, they can decide whether the momentum fits their setup before entering a trade.