Chip Stocks' Eight-Day Slide: The Math of a 15.7% Drop and Why Recoveries Take More

When a market segment falls eight sessions in a row, headlines tend to focus on the cause. This piece focuses on the arithmetic. The numbers behind a drawdown are useful whether or not anyone agrees on why it happened.

What happened

According to Benzinga, the PHLX Semiconductor Index (SOX) fell for eight straight sessions, from Oct. 7 through Oct. 16, 2026. It lost 15.7% over the streak and closed Oct. 16 at 11,137.29.

• The week ending Oct. 16 was down about 11.4%, which Benzinga described as the index's worst week since April 2025.
• Several outlets called the streak the longest since 2008, although at least one compared it with 2006. The exact comparison varies by source.

The popular chip exchange-traded fund SOXX fell about 11.8% over the week, from $559.40 to $493.39, according to Opening Bell Daily News. An ETF is a fund that holds a basket of securities and trades like a stock.

Chip stocks bounced on Monday, Oct. 19, with the Nasdaq reported up about 1.1% that day.

Why it happened is still being debated

Coverage has pointed to several possible contributors, and sources do not agree on a single cause:

• Memory-chip supply worries. Over the weekend of Oct. 10-11, Chinese memory maker CXMT said it was advancing a denser memory design, which some investors read as a sign of more supply ahead.
• Comments on AI spending. Broadcom's CEO said capital could become the industry's biggest constraint. The comments were widely discussed.
• Broader market pressures. Other coverage has cited higher oil prices, a 10-year Treasury yield above 5%, and doubts about whether heavy AI spending will pay back.

Each of these is a reported explanation, not a settled one.

The math of a drawdown

A 15.7% decline means a value of 100 became 84.3. To get back to 100, the value has to rise from 84.3 to 100, a gain of about 18.6%, not 15.7%. The deeper the decline, the bigger the gap:

• A 10% decline needs roughly an 11.1% gain to recover.
• A 20% decline needs a 25% gain.
• A 50% decline needs a 100% gain.

This is not a prediction about any index or fund. It is simply how percentages work, and it is one reason large drawdowns get so much attention from people who study risk.

What concentration means

Concentration describes how much of a portfolio or an index depends on a small number of companies or one theme. A fund focused on one industry can move much more than a broad market fund when that industry has a bad stretch, in either direction.

A diversified fund spreads exposure across many industries. That can reduce the effect of any one segment but does not remove market risk.

Specialized funds can rise faster than the broad market in good periods and fall faster in bad ones. The eight-day streak is an example of how quickly a concentrated area can move.

Things to keep in mind

• Past performance, including both the decline and the bounce, does not predict what comes next.
• A short streak and a one-day rebound are small samples. Markets can do either again, or neither.
• All investing involves risk, including the possible loss of principal.

The educational point is simple: percentages behave asymmetrically, and the more concentrated an area is, the more that matters.

Figures come from public reports and may have changed since publication. Past results do not guarantee future outcomes. AskProsper is an educational site, not a licensed investment advisor, and this article is educational commentary on public market events, not personalized investment, trading, or tax advice.