Portfolio Killers: 10 US Stocks That Wiped Out Up to 66% of Investors’ Wealth in 2026
Not every stock went up in 2026. While the AI trade dominated headlines and pushed many technology names to new highs, a group of large US-listed companies moved sharply in the other direction. According to data from Vested Finance, ten US stocks with market capitalisations above $5 billion have fallen between 49% and 66% so far this year. In simple terms, an investor holding the worst performer would have lost about two-thirds of their money in just a few months.
The list matters because these are not tiny, unknown companies. Each one is worth more than $5 billion, which means many mutual funds, exchange-traded funds and retail portfolios hold them. A fall of this size in a large company can quietly damage a diversified portfolio, even when the broader market looks healthy.
Why 2026 Has Been a Difficult Year for Some Stocks
Two big forces shaped the market this year. The first is the AI trade. Money has flowed heavily into a small group of chipmakers, cloud providers and software firms seen as AI winners. That concentration has left less capital for other sectors. When investors crowd into one theme, the companies left outside it often struggle to attract buyers.
The second force is geopolitics. Ongoing tensions around trade, tariffs and regional conflicts have made investors more cautious. Companies with global supply chains, heavy debt or exposure to affected regions have felt the pressure first. In a nervous market, investors tend to sell the weakest names quickly and ask questions later.
How a 50% to 66% Loss Hurts More Than It Looks
Large losses are harder to recover from than many people realise. A stock that falls 50% must then rise 100% just to get back to where it started. A stock that falls 66% must roughly triple to break even. This is why big drawdowns are often called portfolio killers. They do not just reduce returns. They change the math for years to come.
Consider a simple example. An investor puts $10,000 into a stock that later falls 60%. The position is now worth $4,000. To return to $10,000, the stock needs a gain of 150%. Most companies never manage that kind of comeback, especially if the original fall was caused by real problems in the business rather than a temporary market mood.
What Investors Should Take Away
The first lesson is about concentration. Holding a small number of single stocks can produce big wins, but it can also produce losses like these. Position sizing matters. A stock that can fall 66% should never be so large in a portfolio that it threatens your financial goals.
The second lesson is about checking why a stock is falling. Sometimes a decline is a market overreaction. Other times it reflects falling sales, weak guidance, lost contracts or balance sheet stress. The difference matters. Buying a falling stock without understanding the cause is not investing. It is guessing.
The third lesson is about the appeal of crowded trades. The AI theme has been powerful, but it has also pulled attention and money away from other parts of the market. That can create bargains, but it can also leave weaker companies without the support they need. Investors should look at both sides of any popular trend.
Context From Past Market Cycles
This is not the first time large companies have lost half their value in a single year. During the dot-com bust and the 2008 financial crisis, many well-known firms suffered similar or worse declines. Some recovered. Many did not. The pattern is familiar: strong narratives attract money, weak business models get exposed, and investors who did not check the fundamentals pay the price.
For long-term investors, the practical response is steady. Diversify across sectors and geographies. Review holdings regularly. Avoid letting one stock grow so large that a 50% fall would change your plans. And remember that a big loss is not just a number on a screen. It is real money that becomes much harder to earn back.
