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Apr 18, 2025

100 Years of Concentration in the Equity Market—and the Subsequent Bubbles

Over the past century, the U.S. equity market has oscillated between periods of broad diversification and extreme concentration, with a handful of companies at the top commanding an ever‑larger share of total market capitalization. These concentration peaks often coincide with—or even presage—speculative manias and subsequent market contractions. Below, we trace five concentration inflection points—1932, 1964, 2000, 2009, and 2025—and explore how each gave rise to a distinct bubble (or in one case, a post‑crash frenzy).

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1. 2025: AI Mega‑Caps at the Summit

Concentration Peak: As of early 2025, a small roster of “AI darlings”—NvidiaMicrosoft, Google’s parent Alphabet, and a few specialized chipmakers—account for nearly 25% of the S&P 500’s market value. Nvidia alone has exceeded a $1 trillion valuation, riding a tidal wave of investor enthusiasm around generative AI and data‑center acceleration.
Bubble Warning: High‑profile export controls and regulatory scrutiny in key markets (e.g., U.S. export bans to China) have introduced fresh volatility. Yet investors continue pouring capital into a handful of AI‑focused players, echoing past concentration peaks. History suggests that when too much of the market’s value is tied to a narrow group of stocks, any disappointment—earnings misses, policy shifts, or competitive breakthroughs—can trigger outsized sell‑offs.

 

2. 2009: The Financial Crisis & Post‑Crash Leadership

Concentration Through Leading to Rebound?: By March 2009, concentration took on a different flavor: only a few survivors—AppleGoogle, and a handful of other non‑financial conglomerates—were leading the Nasdaq and S&P 500 out of the crisis. Financials, once the largest sector, shrank to under 15% of market cap.
The New Bubble: Although 2009 itself was a trough, it set the stage for an eight‑year bull market dominated by a handful of tech leaders. By 2018, the “Magnificent Seven” (AppleMicrosoftAmazonAlphabetFacebookTesla, and Nvidia) comprised over 40% of the S&P 500’s total capitalization, inflating a new tech‑centric bubble that peaked in late 2021.

 

3. 2000: The Dot‑Com/Tech Bubble Apex

Concentration Peak: As the Internet exploded in the late 1990s, tech and telecom names—MicrosoftCiscoIntel, Sun Microsystems—soared. At its March 2000 peak, the Technology sector made up nearly 33% of the Nasdaq Composite’s total market cap, and the broad S&P 500 was likewise skewed heavily toward a handful of mega‑caps.
Bubble & Bust: The Nasdaq fell by 78% from its peak to its 2002 trough. The two years following the peak saw massive wealth destruction in companies that had little more than a URL and venture‑backed valuations. The concentration in unprofitable tech names meant losses were not broadly dispersed but rather centered in a narrow slice of the market.

 

4. 1964: The “Nifty Fifty” and Mid‑Century Mania

Concentration Peak: In the early 1960s, a group of high‑quality growth stocks—dubbed the “Nifty Fifty”—dominated portfolios. Companies like IBM, Coca‑Cola, Xerox, and Polaroid traded at stratospheric P/E multiples, and by 1964, these 50 names accounted for an outsized slice of the S&P 500’s total market cap.
Bubble & Bust: By 1970, the major market indices had barely budged from their mid‑’60s highs, while the Nifty stocks saw drawdowns of 70–80%. The concentration on a small roster of “one‑decision” stocks amplified volatility and punished those who believed fundamentals alone could defy valuations.

 

5. 1932: From Roaring ’20s Titans to Depression Tumble

Concentration Peak: In the late 1920s, railroads, steel, oil, and utility giants—think U.S. Steel, Standard Oil, AT&T—collectively made up more than 40% of the total market value on the NYSE. When the 1929 crash sent share prices plummeting, those same behemoths were hit hardest.
Bubble & Bust: By mid‑1932, the Dow Jones Industrial Average had collapsed nearly 90% from its peak. The concentration that once powered roaring returns now intensified losses, as investors poured into “safe” blue‑chips only to find there was no refuge. The ensuing Depression would reshape financial regulation and investor psychology for decades.

Why Concentration Breeds Bubbles

  1. Amplified Impact of Sentiment: When investors crowd into a narrow set of names, even small shifts in collective sentiment can cause massive price swings.
     
  2. Valuation Excess: High demand for a few stocks drives valuations well above sustainable levels, as was evident in the Nifty Fifty and dot‑com crazes.
     
  3. Systemic Risk: A concentrated market leaves portfolios vulnerable: a downturn in key sectors hits nearly every investor at once.
     
  4. Feedback Loops: Rising prices attract more flows, which push prices even higher, inflating the bubble until a catalyst reverses the trend.
     

 

Lessons for Today’s Investors

  • Diversification Matters: Spreading capital across sectors and market caps can mitigate the risk of a narrow‑based drawdown.
     
  • Monitor Concentration Metrics: Keep an eye on sector weightings and top‑10 stock share of total market cap—spikes can signal heightened bubble risk.
     
  • Use Risk Management Tools: Hedging strategies or dynamic portfolio rebalancing can protect against extreme sector swings.
     
  • Stay Skeptical of Herd Behavior: Anchor your decisions in fundamentals and valuation discipline, even when the crowd chases the “next big thing.”
  • Expected Returns are low. 

Conclusion

From the railroads and steel barons of the 1920s to today’s AI mega‑caps, periods of extreme market concentration have repeatedly paved the way for spectacular bubbles—and painful busts. By studying these concentration cycles and heeding the lessons of 1932, 1964, 2000, 2009, and 2025, investors can better navigate the fine line between riding innovation’s wave and riding valuations too far. In a market where the top few names can dictate overall performance, understanding—and managing—concentration risk is essential for long‑term success.

Disclaimers and Limitations

Related Ticker: NVDA, MSFT, GOOGL, AAPL, AMZN, META, TSLA, CSCO, INTC, T

Aroon Indicator for NVDA shows an upward move is likely

NVDA's Aroon Indicator triggered a bullish signal on June 20, 2025. Tickeron's A.I.dvisor detected that the AroonUp green line is above 70 while the AroonDown red line is below 30. When the up indicator moves above 70 and the down indicator remains below 30, it is a sign that the stock could be setting up for a bullish move. Traders may want to buy the stock or look to buy calls options. A.I.dvisor looked at 320 similar instances where the Aroon Indicator showed a similar pattern. In of the 320 cases, the stock moved higher in the days that followed. This puts the odds of a move higher at .

Price Prediction Chart

Technical Analysis (Indicators)

Bullish Trend Analysis

Following a 3-day Advance, the price is estimated to grow further. Considering data from situations where NVDA advanced for three days, in of 369 cases, the price rose further within the following month. The odds of a continued upward trend are .

Bearish Trend Analysis

The 10-day RSI Indicator for NVDA moved out of overbought territory on June 13, 2025. This could be a bearish sign for the stock. Traders may want to consider selling the stock or buying put options. Tickeron's A.I.dvisor looked at 41 similar instances where the indicator moved out of overbought territory. In of the 41 cases, the stock moved lower in the following days. This puts the odds of a move lower at .

The Stochastic Oscillator demonstrated that the ticker has stayed in the overbought zone for 11 days. The longer the ticker stays in the overbought zone, the sooner a price pull-back is expected.

The Moving Average Convergence Divergence Histogram (MACD) for NVDA turned negative on June 11, 2025. This could be a sign that the stock is set to turn lower in the coming weeks. Traders may want to sell the stock or buy put options. Tickeron's A.I.dvisor looked at 48 similar instances when the indicator turned negative. In of the 48 cases the stock turned lower in the days that followed. This puts the odds of success at .

NVDA broke above its upper Bollinger Band on June 03, 2025. This could be a sign that the stock is set to drop as the stock moves back below the upper band and toward the middle band. You may want to consider selling the stock or exploring put options.

The Tickeron SMR rating for this company is (best 1 - 100 worst), indicating very strong sales and a profitable business model. SMR (Sales, Margin, Return on Equity) rating is based on comparative analysis of weighted Sales, Income Margin and Return on Equity values compared against S&P 500 index constituents. The weighted SMR value is a proprietary formula developed by Tickeron and represents an overall profitability measure for a stock.

The Tickeron Profit vs. Risk Rating rating for this company is (best 1 - 100 worst), indicating low risk on high returns. The average Profit vs. Risk Rating rating for the industry is 77, placing this stock better than average.

The Tickeron Price Growth Rating for this company is (best 1 - 100 worst), indicating outstanding price growth. NVDA’s price grows at a higher rate over the last 12 months as compared to S&P 500 index constituents.

The Tickeron PE Growth Rating for this company is (best 1 - 100 worst), pointing to worse than average earnings growth. The PE Growth rating is based on a comparative analysis of stock PE ratio increase over the last 12 months compared against S&P 500 index constituents.

The Tickeron Valuation Rating of (best 1 - 100 worst) indicates that the company is significantly overvalued in the industry. This rating compares market capitalization estimated by our proprietary formula with the current market capitalization. This rating is based on the following metrics, as compared to industry averages: NVDA's P/B Ratio (41.841) is slightly higher than the industry average of (9.035). P/E Ratio (46.403) is within average values for comparable stocks, (62.043). Projected Growth (PEG Ratio) (1.784) is also within normal values, averaging (2.284). NVDA has a moderately low Dividend Yield (0.000) as compared to the industry average of (0.020). P/S Ratio (23.981) is also within normal values, averaging (32.378).

Notable companies

The most notable companies in this group are NVIDIA Corp (NASDAQ:NVDA), Broadcom Inc. (NASDAQ:AVGO), Taiwan Semiconductor Manufacturing Company Ltd (NYSE:TSM), Advanced Micro Devices (NASDAQ:AMD), Texas Instruments (NASDAQ:TXN), Applied Materials (NASDAQ:AMAT), QUALCOMM (NASDAQ:QCOM), Micron Technology (NASDAQ:MU), Lam Research Corp (NASDAQ:LRCX), Analog Devices (NASDAQ:ADI).

Industry description

The semiconductor industry manufacturers all chip-related products, including research and development. These chips are used in innumerable electronic devices, including computers, cell phones, smartphones, and GPSs. Intel Corporation, NVIDIA Corp., and Broadcomm are some of the prominent players in this industry. Semiconductor companies usually tend to do well during periods of healthy economic growth, thereby inducing further research and development in the industry – which in turn augurs well for productivity and growth in the economy. In the near future, demand for semiconductor products (and possibly innovation within the segment) should only expand further, with the proliferation of 5G, autonomous vehicles, IoT, and various AI-driven electronics set to herald a new, advanced chapter in the technology-driven world as we know it. With burgeoning prospects comes great competition. In 2015, SIA estimated that U.S. semiconductor industry ranks as the second most competitive U.S. industry out of 2882 U.S. industries designated manufacturers by the U.S. Census Bureau.

Market Cap

The average market capitalization across the Semiconductors Industry is 55.77B. The market cap for tickers in the group ranges from 13.43K to 3.51T. NVDA holds the highest valuation in this group at 3.51T. The lowest valued company is CYBL at 13.43K.

High and low price notable news

The average weekly price growth across all stocks in the Semiconductors Industry was 2%. For the same Industry, the average monthly price growth was 9%, and the average quarterly price growth was -2%. PXLW experienced the highest price growth at 100%, while ICG experienced the biggest fall at -34%.

Volume

The average weekly volume growth across all stocks in the Semiconductors Industry was 57%. For the same stocks of the Industry, the average monthly volume growth was -4% and the average quarterly volume growth was -19%

Fundamental Analysis Ratings

The average fundamental analysis ratings, where 1 is best and 100 is worst, are as follows

Valuation Rating: 55
P/E Growth Rating: 58
Price Growth Rating: 56
SMR Rating: 72
Profit Risk Rating: 76
Seasonality Score: 3 (-100 ... +100)
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