Most recently, billionaire investor Ken Griffin has been in the headlines because his Citadel hedge fund extended a lifeline to help save Leopold Aschenbrenner’s Situational Awareness.
Some market-watchers seem surprised that Aschenbrenner is already back to making big bets for Situational Awareness, but Griffin is probably not one of them.
During a 2025 appearance on the Founders Podcast, the Citadel boss characterized taking losses and selling as a necessary part of the business.
“You're always selling,” said Griffin. “And if you don't like to sell, here's my advice: Get over it.”
His admonition sounds simple, but that terse “get over it” represents one of the most psychologically demanding principles in active money management: the discipline to cut positions, take profits, or exit losing trades without emotional attachment.
Griffin, who built Citadel into one of the world's most successful hedge funds, understands that the inability to sell is often the single biggest impediment to long-term trading success. His philosophy stands in instructive contrast to the buy-and-hold approach championed by investors like Warren Buffett, and the distinction between these two frameworks is essential for traders navigating today's volatile markets.
The current market environment makes Griffin's message particularly urgent. With the S&P 500 Index ($SPX) up nearly 13% year to date as of early August 2026 and elevated CAPE ratios between 40 and 41, traders face a market where concentration risk in artificial intelligence (AI)-related stocks is extreme and valuations leave little margin for error.
The recent near-collapse of the AI-focused hedge fund Situational Awareness, which lost 67% in July due to concentrated leveraged positions and forced selling during an AI stock selloff, illustrates precisely what happens when the refusal or inability to sell meets margin calls. The fund's close call demonstrates that even a correct thesis can destroy capital when position management fails.
Griffin's selling discipline is fundamentally about survival and capital preservation. The strategy paradox, where the same concentrated approaches that produce spectacular success also produce spectacular failure, means traders must actively manage risk through timely exits.
However, FINRA data showing customer margin debt surging 49% to $1.5 trillion by June 2026 indicates that many market participants are ignoring this wisdom, increasing leverage rather than maintaining the flexibility to sell when conditions deteriorate.
The practical application of Griffin's philosophy requires traders to distinguish between investing and trading timeframes. A buy-and-hold investor can afford patience through drawdowns because their horizon extends decades. An active trader operating with leverage, concentrated positions, or short-term objectives cannot.
The South Korean market, where 1.2 million retail margin accounts received margin calls from leveraged semiconductor ETFs, shows that refusing to sell voluntarily often results in being forced to sell at the worst possible moment.
For today's traders – who are facing elevated valuations, geopolitical risks from the Middle East driving oil prices higher, a deeply divided Federal Reserve, and AI sector concentration that accounts for roughly 20% of the S&P 500 in semiconductor stocks alone – Griffin's advice is best translated into concrete actions.
That includes maintaining stop-loss discipline, sizing positions so that no single loss is fatal, taking partial profits as targets are reached, and treating selling as an integral part of the trading process rather than an admission of defeat.
The traders who survive and compound capital over decades are not those who never sell, but those who sell deliberately, systematically, and without the emotional paralysis that transforms manageable losses into catastrophic ones.
For more insights on managing risk in a heavily concentrated market, check out Most Investors Are Missing This Simple Strategy to Minimize Risk and Maximize Returns.
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On the date of publication, Sarah Holzmann did not have (either directly or indirectly) positions in any of the securities mentioned in this article. All information and data in this article is solely for informational purposes. For more information please view the Barchart Disclosure Policy here.
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