In a recent LinkedIn post, Michael Merlin highlights a significant shift in the composition of the S&P 500, warning investors about the increasing concentration risk within the benchmark index. Merlin points out that what was once considered a “safe” and diversified investment is rapidly changing due to the outsized performance and weighting of a select few technology companies.
Merlin draws attention to the current market landscape, noting the dominant presence of just seven companies. As Michael Merlin states:
“Right now, just 7 companies — Apple, Amazon, Microsoft, Alphabet, Meta, Nvidia, and Tesla — make up about 34% of the entire index.”
He contrasts this with historical data, emphasizing how this concentration has grown dramatically. According to Merlin, in 2015, these same companies accounted for only about 12% of the index. This substantial increase, often referred to as the “Mag 7,” is a critical factor for investors to consider, as it fundamentally alters the risk profile of the S&P 500.
The Fragility of a Top-Heavy Index
Michael Merlin argues that this level of concentration introduces significant fragility into the market. When a small number of large companies heavily influence an index, their performance can disproportionately affect the overall market. Merlin points out the potential for rapid downturns, stating:
“When heavily weighted stocks fall, major indexes often fall faster than people expect.”
He further illustrates this point by referencing an event earlier in the year when the Mag 7’s weighting dropped from 33% to 27%. Merlin views this swing as a stark reminder of how susceptible the index can become to the movements of a few key players.
Bottoms-Up Strategies and Historical Parallels
Merlin also explores alternative investment strategies that may offer better resilience in such a concentrated market. He observes that a “bottoms-up” strategy with minimal exposure to the dominant tech stocks has historically performed better during market pullbacks. This suggests that a diversified approach, focusing on individual company fundamentals rather than broad index tracking, could be a more robust way to navigate current market conditions.
Furthermore, Michael Merlin draws parallels to a significant historical event, noting:
“There are some uncomfortable parallels to the 1999–2000 tech bubble, when TMT stocks made up 45% of the S&P… before collapsing to 20%”
This historical comparison serves as a cautionary tale, reminding investors of the potential for dramatic market corrections when specific sectors become overly dominant.
Understanding Concentration Risk
For everyday investors, particularly those with retirement accounts, index funds, or ETFs tied to the S&P 500, Merlin stresses that this is not mere market trivia. He frames it as a critical issue of concentration risk. Understanding this risk, according to Merlin, is essential for wealth preservation.
Merlin concludes by posing a question to his audience, gauging their awareness of the Mag 7’s current market share. He implicitly encourages a deeper dive into understanding these market dynamics, suggesting that informed investment decisions are crucial in the face of evolving market structures.
📝 About This Content
This article is based on insights shared by Michael Merlin on LinkedIn.
📅 Originally posted on March 2, 2026 | View original post on LinkedIn →