QuantumScape and Applovin Among Q3 Large-Cap Top Stocks - QuantumScape (NYSE:QS)

The Russell 1000 Index posted a strong overall performance in Q3, closing the quarter up around 7%. However, the average stock returned about 4% which indicates that the largest gains were driven by a handful of high-flying names.

Here's a look at the outperforming stocks that led the index in quarterly gains.

QS stock is climbing. See the real-time price action here.

Top Gainers Over 100%

The Russell 1000 saw its best-performing stocks dominated by four standouts, which each gained over 100%.

Sandisk Corp. (NASDAQ:SNDK) had an extraordinary 150% run in the third quarter of 2025. Sandisk is one of the five largest suppliers of NAND flash memory semiconductors globally, and analysts view the company as well-positioned to benefit from AI demand and tight supply.

Astera Labs, Inc. (NASDAQ:ALAB) surged 111% due to remarkable revenue growth—up 149.5% year-over-year to $191.93 million—and strong demand for AI connectivity solutions.

Applovin Corp. (NASDAQ:APP) posted 102% gains in the third quarter, driven by sector-wide tailwinds.

MP Materials Corp. (NYSE:MP) benefited from massive investor interest after a $400 million investment from the Trump administration and a $500 million supply agreement with Apple, Inc. (NASDAQ:AAPL).

Gainers Over 70%

An additional four stocks in the Russell 1000 posted gains of more than 70% during the quarter:

Western Digital Corp. (NASDAQ:WDC) continued to benefit from data center build-out trends, and its stock surged 84% in the quarter.

QuantumScape Corp. (NYSE:QS) posted outsized returns on retail investor interest and optimism for its solid-state battery technology and expansion efforts.

Ciena Corp. (NYSE:CIEN) rose due to surging demand for AI-driven networking solutions and major cloud provider investments.

Wayfair, Inc. (NYSE:W) gained 70% in Q3, driven by strategic moves in ecommerce and retail technology.

These massive upswings were central to the broader market's outperformance, demonstrating that the market in 2025 has been highly favorable for innovative tech and AI-related stocks.

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