Marvell Technology saw a notable surge of approximately 13% on Monday, following its invitation to join the S&P 500 index. This move often compels index funds to acquire shares, which typically leads to increased trading activity from investors eager to capitalize on the anticipated influx of capital.
However, there’s a critical nuance to consider. Historical analysis from Yahoo Finance, which examined 1,926 additions to the S&P 500 dating back to 1957, suggests that while stocks often experience a pre-inclusion performance boost, they tend to underperform the broader market post-inclusion. In the days leading up to their entry, stocks aiming for S&P 500 membership typically outperform the index; research indicates that the median stock beats the S&P 500 by about 3.3% during the 25 trading days prior to joining.
Marvell’s upcoming inclusion, set for June 22, may have already harnessed some of this pre-entry momentum, posing a challenge for future performance expectations. Historically, returns for stocks added to the index indicate a decline in relative performance shortly after entry. Specifically, analyzing data from 2010 to the present reveals that the median stock added to the S&P 500 trailed the index by approximately 1% after one quarter and nearly 8% after a year, with around 60% of stocks struggling to keep pace with the S&P 500 one year later.
The observed trends have transformed over the decades. Prior to 1990, the addition effect was minimal, but from 1990 to 2009, as passive investing gained traction, the phenomenon became increasingly pronounced. Since 2010, the bullish sentiment around index memberships has shifted earlier, encouraging hedge funds and astute investors to speculate on forthcoming index adjustments ahead of the official changes.
Despite this trend, joining the S&P 500 does not guarantee lasting success. Examples of significant post-inclusion performance include Palantir, which experienced remarkable growth, while companies like Super Micro Computer, Netflix, and PENN Entertainment demonstrate that fundamental strengths can often outweigh index-related advantages.
For Marvell, the impending S&P 500 inclusion means initial demand is expected to propel the stock into June 22. The real challenge lies ahead, as Marvell must demonstrate whether the initial boost from index membership serves as a catalyst for sustained growth or merely represents the peak of pre-inclusion enthusiasm.
