The Retail Investor at Two Speeds: The American Casino vs. the Cautious Spanish Saver

At the end of June, Citadel Securities published its semiannual review of market structure and flows, authored by Scott Rubner. Its thesis is as simple as it is uncomfortable: to understand markets in 2026, it is no longer enough to look at macroeconomic variables—growth, inflation, earnings. We must begin by understanding what they call the “structure of the market itself.” Concentration, passive investing, retail participation, leverage, and volatility have ceased to be isolated trends and have become the forces that determine how capital moves.

The data point that interests us most from Spain is the portrait it paints of the American retail investor. And it is worth holding that portrait up to a mirror: in many respects, the Spanish saver behaves in exactly the opposite way. It is worth understanding why—and what we should learn from both.

The American Retail Investor Now Moves the Market

Citadel has a privileged vantage point: it is the leading market maker for U.S. retail order flow, executing around 35% of all retail equity trading in the U.S. stock market. From that position, it describes an individual investor who has evolved from a cyclical phenomenon into a permanent source of demand. Some highlights from the first half of 2026:

• Record trading volumes: Retail cash equity trading volumes were 65% higher than in 2025 and more than double the average recorded in 2024. Nine of the ten busiest trading days in Citadel’s history occurred during May and June.
• Buy the dip, taken to the extreme: On days when the S&P 500 declined, retail investors bought approximately 3.5 times their average daily amount—the most aggressive buy-the-dip behavior ever recorded in Citadel’s historical data.
• Extreme trading: the culture of same-day expiration: Retail investors traded a record $6.8 billion in options premiums per day during June. More importantly, those trades were concentrated in extremely short-dated options: contracts expiring the same day (0DTE) now account for nearly half of all retail options volume, with an average time to expiration of less than three days.

• Chasing market leaders with leverage: Much of this activity was concentrated in semiconductors, with roughly $1.9 billion in daily options premiums traded during June. Approximately 75% of this volume consisted of call options and leveraged ETFs, whose assets reached a record $218 billion.

The backdrop is one of extreme market concentration: the ten largest companies now account for almost 40% of the S&P 500, while semiconductor companies represent nearly one-fifth of the index. Rather than diversifying away from this concentration, American retail investors embrace it—using leverage and focusing on very short-term trades.

The Spanish Mirror: The Cautious Saver

Now let’s cross the Atlantic. The latest figures from the Inverco Observatory paint a very different picture.

The preferred investment vehicle for Spanish retail investors is not 0DTE options or leveraged ETFs—it is the investment fund. Assets under management in Spanish investment funds closed 2025 at a record €450.9 billion, following nearly €52 billion in net inflows during the year—the highest annual inflow ever recorded—and now amount to 26.7% of Spain’s GDP. Unlike the rest of Europe, investment funds in Spain remain overwhelmingly retail products: households own 62% of total fund assets.

It is well known that investment funds in Spain enjoy significant tax advantages—capital gains taxation is deferred until money is withdrawn, and investors can switch between funds without triggering taxable events—which partly explains this concentration.

However, the real difference lies in how Spaniards invest:

• A conservative rather than speculative bias. Within investment funds, fixed-income and money market funds increased their share during 2025, rising from 43.3% to 46.8% of total assets. Pure equity funds account for only 17.1%, and their share even declined slightly despite rising stock markets.
• A slow move away from bank deposits. Bank deposits and cash still represent 32.5% of households’ financial assets. Their weight has declined, but by only 1.3 percentage points over the year. Since 2015, over an entire decade, deposits have barely lost ground in Spanish household wealth, falling only from 32.9% to 32.5%.
• Delegation rather than trading. The number of investment fund accounts surpassed 17.8 million (+7.5%), with most of the growth driven by discretionary portfolio management and professionally advised portfolios. Spaniards who decide to invest tend to delegate investment decisions rather than trade on their own.
• A long-term horizon. Nearly two-thirds of fund investors have remained invested for more than four years.

Where the American investor buys the dip using one-day call options on Nvidia—or other semiconductor companies—the Spanish investor slowly transfers money from a bank deposit into a money market, fixed-income, or balanced fund and leaves it invested for years.

These are two almost opposite financial cultures.

Where Spain Does Resemble the United States

It would be a mistake to portray Spanish savers as immune to global financial trends. There are three channels through which the American model is making its way into Spain:

1. Neobrokers. Some of the new digital investment platforms are attracting millions of clients across Europe with solutions designed for a new generation of digitally savvy investors, where usability and ease of access are key drivers of adoption.
2. Crypto. Its adoption continues to grow, although cautiously: most retail investors allocate less than 5% of their capital to cryptocurrencies, and many invest only occasionally, taking advantage of market downturns.
3. The same concentration. When Spanish investors buy global equities through index funds or ETFs, they end up—often unintentionally—buying into the same concentration of mega-cap technology companies and semiconductor stocks that dominates the S&P 500. American market concentration has also become, indirectly, our own.

The Differences That Really Matter

Even so, the gap remains enormous—and in some respects, it favors the Spanish saver. The systematic use of leverage by retail investors, same-day options, leveraged ETFs, and expensive borrowing documented by Citadel in the United States is virtually nonexistent among individual investors in Spain.

This is no coincidence. For years, Spain’s securities regulator (CNMV) has warned that CFDs and other leveraged products are not suitable for retail investors, precisely because the vast majority of those who use them lose money.

The result is a Spanish retail investor who, despite all of their shortcomings—holding excessive idle cash, maintaining a strong preference for fixed income, and showing a long-standing reluctance to invest in equities—tends to make mistakes born of excessive caution rather than excessive risk-taking.

In the United States, the main risk for retail investors is becoming trapped in a market driven by its own leveraged enthusiasm. In Spain, the risk is the opposite: losing purchasing power by leaving too much money sitting idle.

Neither Casino nor Bank Deposit: The Virtuous Middle Ground

If we had to choose between the two flaws, the Spanish one is undoubtedly the less risky.

But neither extreme should be the goal.

Citadel’s report is, perhaps unintentionally, a compelling argument in favor of long-term, diversified, index investing. The American retail investor demonstrates that frantic activity—buying every dip, chasing the hottest sector, leveraging short-term bets—has become a structural force in today’s markets… but also a structural source of risk for those who engage in it.

Spanish investors, by contrast, demonstrate that gradually moving savings from bank deposits into collective investment vehicles is a sensible approach. However, that transition remains painfully slow, and many investors stop halfway, allocating too much to fixed income and money market funds, thereby limiting their long-term return potential.

It is worth remembering that keeping our savings in bank deposits or money market funds exposes us to the quietest risk of all: inflation. We do not perceive inflation risk in our current accounts or deposits because there is no visible volatility—our account balance never changes. But this is more than a risk; it is a certainty that our savings will inevitably lose purchasing power over time.

The virtuous middle ground lies in neither of these extremes. It is a global, diversified, low-cost, long-term investment approach that captures the growth of financial markets without depending on timing the market or picking the next fashionable stock.

Neither the casino of Wall Street nor the eternal bank deposit.

The good news is that Spanish savers are gradually moving in that direction. Moreover, the growth in discretionary portfolio management suggests that when they do decide to invest, they tend to do so in a sensible and disciplined way.

At the same time, more proactive Spanish investors should continue learning as they gain a better understanding of risk and progressively achieve their financial goals, while also exploring other ways of investing.

Sources: Citadel Securities, 1H 2026 Market Structure & Flows (Scott Rubner, June 30, 2026); Inverco Observatory (2025 year-end data); Spanish National Securities Market Commission (CNMV).