Tracking The Top S&P 500 Stocks Last Week – WDC, GOOG And More

September 8th, 2025 by Trefis Team
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During the week ending September 5, the S&P 500 remained relatively flat, down 0.12%. This was in contrast to several individual S&P 500 stocks, particularly those in the AI sector, which saw strong gains. The top movers were driven by a combination of factors, including positive quarterly earnings surprises, significant chip deals, and favorable regulatory outcomes.

Macroeconomic data for the week indicated signs of a weakening labor market, with nonfarm payrolls increasing by only 22,000 in August, significantly below the forecast of 75,000. Additionally, the unemployment rate rose to 4.3%. This data reinforces the expectation that the Federal Reserve will proceed with its widely anticipated interest rate cut later this month. We will discuss the top-moving stocks in more detail below.

That being said, if you seek an upside with less volatility than holding an individual stock, consider the High Quality Portfolio. It has comfortably outperformed its benchmark—a combination of the S&P 500, Russell, and S&P MidCap indexes—and has achieved returns exceeding 91% since its inception.

1. Western Digital (NASDAQ: WDC): Surging with AI Demand

Western Digital’s stock jumped 15% last week following a robust earnings report and optimistic growth projections for upcoming quarters. WDC has nearly doubled its value in 2025, benefiting from the AI boom as its high-performance data storage solutions are integral to AI data center infrastructure. At a price of $93, WDC trades at about 2x trailing revenues, which is slightly above its five-year average P/S ratio of 1.7x. The stock’s lower valuation, especially when compared to some of its peers, stems from factors including its greater exposure to the volatile NAND segment, recent market downturns, and historical concerns over cyclical earnings stability.

2. Broadcom (NASDAQ: AVGO): Broadcom’s Big AI Chip Deal

Broadcom’s stock rose 13% last week, powered by impressive quarterly results and the announcement of a new $10 billion custom AI chip order from a major client, which investors expect will meaningfully accelerate revenue growth. Our recent analysis – AVGO Stock To $400 – talks about Broadcom’s potential for another two-fold gain after rising 135% in the last twelve months. The company is leveraging its expertise in semiconductor fabrication, targeting bespoke AI hardware solutions for hyperscale, cloud, and enterprise.

3. Seagate (NASDAQ: STX): High Valuations Amid AI Hype

Seagate Technology saw its stock gain 12%, also driven by anticipation of sustained AI storage demand, with the stock price up 115% year to date. The enthusiasm around high-capacity storage for AI workloads has propelled STX’s market price, now trading at 4x trailing revenues—far above its five-year average of 1.9x. This signals a premium valuation, hinting investors expect elevated demand and earnings to persist.

S&P 500 Top Gainers For The Week Ending Sep 5

4. Micron (NASDAQ: MU): Riding the Memory Upcycle

Micron’s stock climbed 10%, primarily thanks to rising demand for high-bandwidth memory (HBM) needed in AI infrastructure. Micron’s revenue multiple stands at 3.9x, nearly matching its five-year average, suggesting pricing reflects both current strength and cyclical risks—especially as the DRAM market has finally entered an upcycle after a tough 2024, in contrast to a still-depressed NAND market. Memory stocks like Micron are cyclical, often trading at lower multiples when earnings peaks are anticipated because markets price in the likelihood of future cyclic downturns. Still, despite its recent rise, Micron may be the AI’s best bargain.

5. Alphabet (NASDAQ: GOOG) Regulatory Win in Focus

Google gained 10% following a key regulatory victory—a federal court ruled it would not have to divest its Chrome browser, a platform we think is worth over a trillion to Google’s ecosystem. The stock remains relatively undervalued versus peers, with potential for an additional trillion-dollar increase should further favorable rulings occur; notably, another court decision is expected on September 10 to influence the next trajectory for the stock.

Remember, there always remains a meaningful risk when investing in a single stock, or just a handful of stocks. Consider the Trefis High Quality (HQ) Portfolio, which, with a collection of 30 stocks, has a track record of comfortably outperforming the S&P 500 over the last 4-year period. Why is that? As a group, HQ Portfolio stocks provided better returns with less risk versus the benchmark index; less of a roller-coaster ride, as evident in HQ Portfolio performance metrics.

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