These 3 Stocks Led the S&P 500 in September 2025

The S&P 500 (SNPINDEX: ^GSPC) index just posted its strongest September in 15 years, gaining 3.5% during the month. Technology stocks led the way, with some absolutely crushing the index with over 50% gains. Here's a look at the three top-performing S&P 500 stocks from September and what drove them higher.

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1. Warner Bros. Discovery

Shares of Warner Bros. Discovery (NASDAQ: WBD) surged 67.8% in September on takeover speculation. On Sept. 11, The Wall Street Journal reported that Paramount Skydance, which was acquired by the Ellison family (owners of Oracle), was preparing a "majority cash bid" for Warner Bros.

Warner Bros. stock hit a 52-week high of $20.24 on Sept. 25. While it's unclear whether a merger will ever happen, management has plans to split into two companies by mid-2026, separating its streaming business and studios from its global TV networks business.

2. AppLovin

AppLovin (NASDAQ: APP) joined the S&P 500 index on Sept. 22, but the stock went higher right after S&P Dow Jones announced the upcoming addition on Sept. 5. With several analysts also lifting their price targets on AppLovin, the stock skyrocketed 50.1% in September.

The company's platform helps mobile app developers and marketers monetize their apps, mainly through advertising. But the stock is under pressure this month after a Bloomberg report stated that the Securities and Exchange Commission is probing AppLovin's data collection practices.

3. Western Digital

Shares of Western Digital (NASDAQ: WDC) soared 49.4% in September and hit a 52-week high of $137.40 on Oct. 2. At least seven analysts raised their price targets on the stock last month amid booming demand for artificial intelligence and cloud computing, both of which require large-scale data storage. Western Digital is among the largest manufacturers of hard-disc drives (HDD), flash products, and storage devices in the world.

Analysts at Morgan Stanley raised Western Digital's price target from $99 to $171 per share, citing the stock's low valuation despite the huge potential demand for HDDs amid rising cloud spending.

Neha Chamaria has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Oracle and Warner Bros. Discovery. The Motley Fool has a disclosure policy.