These Were the 5 Worst-Performing Stocks in the S&P 500 in August 2025

Five S&P 500 constituents—The Trade Desk, Super Micro Computer, Gartner, Fortinet, and Coinbase—experienced significant declines of 19-37% in August, driven by disappointing quarterly financial results. The Trade Desk's outlook was dampened by slow revenue growth guidance and a CFO change, while Super Micro Computer's strong sales were overshadowed by record-low gross margins. Gartner provided weak full-year growth projections, Fortinet raised concerns regarding its refresh cycle, and Coinbase signaled a potential 'crypto winter' amid declining transaction revenue. While Coinbase is identified as most vulnerable, Super Micro Computer is presented as a potential opportunistic buy, citing robust AI-driven demand and an attractive valuation, contingent on a recovery in gross margins.

Analysis

Five S&P 500 constituents—The Trade Desk (TTD), Super Micro Computer (SMCI), Gartner (IT), Fortinet (FTNT), and Coinbase (COIN)—were the index's worst performers in August, with stock prices declining between 19% and 37% following their respective quarterly financial reports. The sell-offs were driven by company-specific issues rather than a single market trend. The Trade Desk's stock was impacted by its Q3 2025 revenue growth guidance of 14%, its slowest rate as a public company outside the pandemic, which was exacerbated by an abrupt CFO change. Gartner, despite beating Q2 2025 estimates, guided for a meager 2% full-year growth, raising concerns about its upside potential. Fortinet's stock plunged due to analyst worries about its firewall refresh cycle, with management's attempts to downplay a potential growth slowdown in 2027 failing to reassure investors. Coinbase appears fundamentally weakest, with Q2 2025 results showing falling revenue, rising expenses, and a sharp drop in transaction revenue, signaling a potential 'crypto winter'. In contrast, Super Micro Computer's decline was driven by a record-low Q4 gross margin of 9.5%, which overshadowed strong fiscal 2025 sales growth of 47% and a fiscal 2026 growth forecast of at least 50%, fueled by AI demand. The investment case for SMCI hinges on management's ability to achieve its long-term gross margin target of 15-16%.

Key Decisions for Investors

• Investors should distinguish between the drivers of underperformance; Coinbase faces fundamental deterioration, while the sell-offs in TTD, FTNT, and IT were primarily driven by decelerating growth guidance.
• For investors with a higher risk tolerance, Super Micro Computer may present a growth-at-a-reasonable-price opportunity, but any position should be contingent on monitoring for evidence of gross margin recovery toward the 15-16% target.
• Extreme caution is warranted with Coinbase, as deteriorating transaction revenues and management's negative outlook strongly suggest a cyclical downturn that could lead to further downside pressure.
• Consider holding or re-evaluating positions in Gartner, Fortinet, and The Trade Desk based on future quarterly reports, as their current weakness is tied to forward outlooks which may be revised, rather than a collapse of their core businesses.