Inflation, not growth, now drives markets and that has reshaped risk, volatility and valuations

Market Analysis

Markets have changed materially over the past decade, and Piper Sandler strategists say the dominant risk for investors today is inflation not slowing growth. In a note this week, a team at the Minneapolis-based investment bank led by Michael Kantrowitz highlighted five key shifts that have altered how equities respond to economic news and policy decisions.

The most important shift is psychological: until recently, investors worried more about economic deceleration than about rising prices. From the late 1990s through the immediate aftermath of the COVID-19 shock, growth and recession risk were front of mind. Today, however, market moves are driven sharply by inflation prints and by the Federal Reserves interest-rate decisions. Piper Sandlers strategists say investors now fear higher inflation and the interest-rate increases it brings more than they fear slower growth.

That change in the dominant fear has altered market dynamics in other ways. Volatility patterns as measured by beta relative to the broader market have flipped between value and growth. Historically, large-cap value tended to be higher beta and more cyclical; large-cap growth was lower beta. In the current environment, large-cap value has behaved more defensively, while large-cap growth, especially companies tied to artificial intelligence and other Big Tech leaders, has become the higher-beta cohort.

Concentration in U.S. equities has also accelerated. The combined market capitalization of U.S. stocks is now almost two and a half times U.S. gross domestic product. Piper Sandler argues that if the market were to fall by a 30% average decline associated with a typical recession, the hit to market value would equal roughly 70% of U.S. GDP a level of systemic importance that may lower the threshold at which policymakers step in to support markets.

Equity concentration is pronounced at the top: the 10 largest stocks account for more than 40% of the S&P 500, the strategists note. Technology earnings have outpaced other sectors, and each member of the so-called Magnificent Seven is held by roughly 8,000 mutual funds, underscoring both their market influence and the crowding of investor exposures.

Another notable evolution is that valuation has become a less reliable stock-selection tool. While value outperformed through the 1980s and 1990s, since the global financial crisis of 200809 more expensive companies have tended to outperform consistently. Elevated valuations for the broader market have not produced the lower returns that historical relationships would have suggested, the note says.

What this means for investors

Piper Sandlers view implies investors should recalibrate how they think about risk. Where once slowing growth and recession odds might have dominated portfolio positioning, inflation surprises and central-bank responses now have outsized influence on asset prices. That can change which sectors and styles are treated as defensive or risky, and it complicates traditional diversification strategies when a handful of large-cap names dominate index returns.

The banks strategists caution that markets will still rise and fall, but they expect policymakers willingness to intervene may be greater than in earlier eras because of the large economic exposure embedded in todays market capitalisation. At the same time, with valuation metrics proving less predictive, investors face a tougher environment for picking winners on the basis of price alone.

Taken together, the shifts Piper Sandler identifies an inflation-dominated risk landscape, changing beta dynamics between growth and value, extreme market concentration, and weaker valuation signals suggest that portfolio construction and risk management may need to adapt to a market where inflation and monetary policy drive the scoreboard more than headline growth figures.

Investors who treat those forces as the primary market drivers and who consider concentration and policy risk in their allocations may be better positioned for the next swing in markets.