What We Know About Super Micro's 60.86% Drop Since Joining the S&P 500

Super Micro Computer's stock has lost 60.86% of its value since the company joined the S&P 500, according to 24/7 Wall St., and funds built to track that index — including Vanguard's S&P 500 ETF (VOO) — had no choice but to buy and hold the stock as it fell.

How much has Super Micro's stock fallen since joining the S&P 500?

The 60.86% figure comes from 24/7 Wall St.'s comparison of Super Micro's share price at the time of its S&P 500 inclusion against its current trading level. The outlet frames the decline as a case study in what happens when a volatile stock gets added to the benchmark that most U.S. retirement savers are exposed to through 401(k)s and index funds.

Down 60.86% since joining the index — and funds like VOO were required to buy it anyway. — 24/7 Wall St.

By the numbers:

• 60.86%: Super Micro's decline since being added to the S&P 500, per 24/7 Wall St.
• VOO: Vanguard's S&P 500 ETF, one of the passive funds that must hold every current index constituent, including Super Micro, by design rather than by choice.

Why did index funds like VOO have to buy Super Micro anyway?

VOO and similar S&P 500 index funds are not actively managed. Their mandate is to replicate the index's holdings and weightings as closely as possible, not to judge whether a given stock looks cheap, expensive, or risky. When S&P Dow Jones Indices adds a company to the S&P 500, every fund tracking that index adds the same stock at roughly the same time, regardless of the share price or the company's recent headlines.

That structure is the same across Vanguard's index lineup — the same no-discretion approach shows up in sector-specific products such as the Vanguard Utilities Index Fund ETF (VPU), which holds whatever utilities sit in its target index rather than picking winners. For a broad fund like VOO, that means Super Micro's inclusion — and its subsequent slide — flowed directly into the fund's holdings without any manager stepping in to sell.

Who adds and removes stocks from the S&P 500?

S&P Dow Jones Indices, which maintains the S&P 500, decides additions and removals through its index committee rather than a strict price-based formula. The committee weighs factors such as market capitalization, trading liquidity, and sector balance when deciding which companies represent large-cap U.S. equities. Once a stock is added, it stays in the index — and in every fund tracking it — until the committee removes it, independent of how the share price performs in between.

Does the drop change what a VOO investor actually owns?

The S&P 500 is a market-capitalization-weighted index, meaning each company's share of the index — and therefore its share of a fund like VOO — rises and falls automatically as its stock price moves. A sharp decline like Super Micro's shrinks the company's weight within VOO without any fund manager taking action; the stock simply becomes a smaller slice of the portfolio as its market value falls. 24/7 Wall St.'s reporting does not specify Super Micro's exact weight within VOO, so the overall drag on fund-level returns depends on how large that slice was to begin with.

What to watch next

• Whether S&P Dow Jones Indices' committee revisits Super Micro's standing in the index if its market value or compliance profile shifts further.
• How the stock's weight in VOO and other S&P 500 trackers adjusts at the next scheduled index rebalance.
• Any additional earnings or regulatory updates from Super Micro that move the share price in either direction.
• Commentary from Vanguard or other index-fund sponsors on how passive mandates handle volatile constituents going forward.

For now, the mechanics are straightforward even if the outcome has been painful for some shareholders: S&P 500 index funds are required to hold what the index holds, and Super Micro's 60.86% decline since inclusion is the latest example of that rule playing out in real time, as reported by 24/7 Wall St.