The real question for investors looking at expensive U.S. stocks is not simply whether the market is too high to buy. According to ABMedia, Just Keep Buying author Nick Maggiulli said the first thing to ask is how long the money can stay untouched.
That view comes as the AI boom keeps pushing up valuations in U.S. equities. Some investors have piled into AI and semiconductor names and seen returns rise quickly. Others have kept funds in cash, worried about becoming the last buyers at elevated levels while waiting for a correction that has yet to arrive. ABMedia noted that Berkshire Hathaway’s cash position has also remained near historical highs, adding to concern that valuations may have run too far.
In the interview, recorded about two months ago, Maggiulli revisited the thesis most associated with his work: investors should keep buying regardless of market noise. The discussion was not framed around forecasting next week’s prices or short-term sentiment. Instead, it focused on a recurring late-cycle question: after such a large run-up, is it still reasonable to buy stocks now?
From data analyst to bestselling author
Maggiulli graduated from Stanford University with a degree in economics and now serves as chief operating officer at U.S. wealth management firm Ritholtz Wealth Management. His work covers operations, data science, and business intelligence analysis.
He launched the personal finance blog Of Dollars And Data in 2017, initially with the simple goal of publishing one post a week. Over time, the site became known for data-driven work on investing, saving, and wealth building. In 2022, he published Just Keep Buying, using historical data to tackle common questions such as how much to save, whether to wait for a market decline, whether to buy individual stocks, and when to put money to work.
The core idea of the book is not to find the perfect entry point. It is to build wealth around repeatable behavior over long periods. Maggiulli has reduced that framework to one line: keep buying a diversified set of income-producing assets.
That line contains three parts: ongoing contributions, diversification, and a focus on productive assets such as stocks, bonds, and real estate rather than concentrating everything in one stock, one country, or assets that rely only on price appreciation.
Anthropic changed how he looked at AI growth
Maggiulli pointed to Claude developer Anthropic as an example of why his own market view shifted. He said he had struggled to imagine that an AI company’s annual recurring revenue could jump from about $3 billion to about $45 billion in just one year, yet growth that once looked implausible started to show up in reported business performance.
That, he said, was a major reason he moved from a more bearish stance back toward a more constructive one. The change did not come from deciding AI stocks were cheap. It came from recognizing that some of the aggressive growth assumptions embedded in valuations were being validated by revenue.
“I originally thought those growth expectations were crazy, but the growth really showed up,” Maggiulli said, according to the interview. He added that a number of revenue and profit targets he had once viewed as unrealistic were not only met but exceeded, forcing him to acknowledge that his earlier pessimism may have been wrong.
He did not present Anthropic’s trajectory as proof that every AI company can produce similar results or that any valuation can be justified. The point, rather, was that investors cannot look only at share-price gains. They also need to keep checking whether revenue, enterprise adoption, and commercialization are catching up with the expectations built into the market.
Bubble and paradigm shift can exist at the same time
Maggiulli said he did turn more cautious at one stage over the past year as AI-related valuations climbed quickly, even cutting his stock allocation. He saw features of the market that reminded him of the speculative excess of 2021, and at one point compared Nvidia’s price-to-sales multiple with Microsoft during the 1999 internet bubble.
Then revenue and earnings growth came in stronger than he had expected. Some companies did not merely hit the ambitious targets placed in front of them. They beat them by a wide margin. That prompted him to move back toward a more bullish view.
His conclusion was not that AI has no bubble characteristics. It was that two seemingly conflicting things may both be true. Heavy capital inflows can produce duplicated investment, overstretched valuations, and pockets of excess. At the same time, AI may genuinely reduce work time and production costs, which would make it a real technological shift rather than a simple fad.
Put another way, AI may involve bubble dynamics without being fake. Technological revolutions and capital bubbles can happen together. That is what makes the current market hard to judge: investors have to assess not only how much value AI may create, but also how much future growth stock prices have already priced in.
The stock decision starts with time horizon
Even after becoming more cautious, Maggiulli did not sell out of stocks. ABMedia said he moved from a setup where new money might previously have gone 100% into equities to a mix of about 80% stocks and 20% fixed income, while continuing to invest regularly.
He argued that investors often make the mistake of treating the choice as all stocks or all cash. The first path can expose them to losses they cannot tolerate in a major drawdown. The second can steadily erode purchasing power during a long bull market and in an inflationary environment.
For him, the sensible approach is not to guess when the market will peak. It is to build an allocation that allows an investor to stay invested whether prices keep rising or fall sharply. He also acknowledged that emotion is part of investing. Even if the numbers suggest immediate deployment is usually better, stretching entries across six months or a year may be the more durable option if a lump-sum decision would leave someone unable to sleep.
The deciding factor, he said, is not just valuation. It is when the money will be needed.
If the funds will be used in the next few years for a home down payment, wedding, childcare, tuition, or another known expense, they are not well suited to stock-market risk. Long-term optimism does not guarantee that stocks will be at a favorable level when the bill comes due. In that case, cash, short-term Treasury bills, or other lower-volatility assets are more appropriate.
Maggiulli said his own larger position in short-term Treasuries and cash reflects plans to buy a home, not a call that the AI bubble is about to break. That money has a specific purpose and should not be treated as dry powder waiting to buy a market dip.
On the other hand, if the money will not be used for 10 years, 20 years, or until retirement, short-term moves matter much less. For long-horizon investors, historical data has generally favored ongoing contributions into diversified productive assets over waiting for a bottom that cannot be forecast with consistency.
His rule can be reduced to a simple version: the shorter the time horizon, the more conservative the allocation should be. The longer the time horizon, the more room there is to absorb equity volatility.
Waiting for a crash can still leave you paying more
Many investors assume that patience brings a safer entry. Maggiulli pushed back on that idea, saying markets can rise for a long stretch before the eventual drawdown arrives.
He used the example of an investor who began waiting for a U.S. stock-market crash in 2017. Even if that person managed to buy at the exact bottom of the March 2020 pandemic selloff, the purchase price could still have been above the level available back in 2017.
That is why “buy after the drop” does not automatically mean “buy at a cheaper price.” The comparison that matters is not how much the market fell from peak to trough. It is whether the final purchase price is actually below the level that was available on the day the investor first decided to wait.
He also noted that investors rarely know when a decline is over. A 20% drawdown may look attractive and then turn into another 30% drop. Even a 50% fall does not guarantee the market will not halve again.
For that reason, Maggiulli does not support holding large cash balances solely to wait for a crash. In his view, cash should map to specific needs such as an emergency reserve, a home down payment, wedding costs, or near-term living expenses. If the only reason to hold it is the hope of buying lower later, history usually does not support the strategy.
Lump sum or phased buying
Maggiulli said dollar-cost averaging often gets used to describe two different situations.
- The first is investing new savings from each paycheck as they become available. That is the kind of steady buying he supports.
- The second is sitting on a large cash pile and deliberately spreading deployment across months or even years.
In the second case, he usually favors investing all at once because the stock market has had a higher long-term probability of rising than falling. The later the money enters, the greater the opportunity cost if prices continue moving up. He summarized the principle as: buy quickly, sell slowly.
Based on the historical estimates he cited in the interview, spreading a lump sum over 12 months instead of investing it immediately could reduce average returns by about 4%. If the deployment period is six months, the gap may narrow to roughly 2%.
He still sees a place for phased buying as a form of psychological insurance. An investor may give up some expected return in exchange for less anxiety about entering right before a crash. The important issue, in his view, is not which method wins in a theoretical vacuum. It is which method actually gets the investor into the market rather than leaving the decision unmade.
What about concentration in the S&P 500
As companies such as Nvidia, Microsoft, and Apple have taken a larger weight in the S&P 500, passive investors have started to ask whether buying the index now amounts to a concentrated technology bet.
Maggiulli acknowledged that the technology weight in the index has risen, but said the S&P 500 still spans sectors including financials, energy, healthcare, and consumer businesses. In his view, that still leaves it more diversified than many smaller markets dominated by only a handful of large firms.
He added that investors can lower concentration in other ways, including international stocks, equal-weight indexes, bonds, or real estate investment trusts. The central goal is not to avoid U.S. technology entirely. It is to avoid having total wealth tied to the same set of companies.
He said the more dangerous mistake is to own Nvidia, Microsoft, and Apple at the same time and assume that counts as broad diversification. The businesses are different, but they remain highly exposed to overlapping drivers such as technology spending, AI capital expenditure, and the valuation of large U.S. growth stocks.
He holds Bitcoin at about 2%
Although the framework behind Just Keep Buying centers on assets with cash flow or productive capacity, Maggiulli said he does not oppose owning gold, art, or Bitcoin. He simply does not think those assets should make up the core of a portfolio.
He said historical asset-allocation modeling suggested that, under certain risk conditions, adding roughly 2% Bitcoin could improve a portfolio’s risk-return profile. As a result, he has kept Bitcoin at around 2% of his allocation for years.
When Bitcoin rises sharply and grows beyond that target, he sells part of the position and rebalances back to 2%. When it falls and approaches or drops below the target weight, he may add some back. In other words, he is not trying to trade Bitcoin by forecasting price. He treats it as a small hedge and a nontraditional asset.
Nonproductive assets including Bitcoin, gold, and art account for only a small share of his overall portfolio. Most of his capital remains in U.S. and international equities, short-term bonds, and REITs.
That approach offers a middle ground between going all in on Bitcoin and avoiding crypto entirely. Investors can admit they do not know whether Bitcoin will become a major long-term asset while still taking limited exposure to potential upside without allowing it to determine their financial outcome.
The biggest risk in crypto is not missing out
When speaking about performative investing culture on social media, Maggiulli singled out crypto investors. In bull markets, he said, platforms fill up with stories about making millions through Bitcoin, altcoins, or NFTs. What people usually see, though, is the unrealized gain in the middle of the story rather than the final result.
He described cases in which crypto investors built positions worth tens of millions of dollars and, at least in theory, could have shifted into lower-risk assets and lived on the proceeds for life. Instead, they stayed in, took on more risk, and gave back much of what they had made in the next downturn.
He also mentioned a friend who bought a Solana Monkey NFT. The initial investment was only a few hundred dollars, and the position at one point was worth more than $1 million. After the market crashed, the friend ultimately sold for about $90,000. That was still a huge gain, but it represented a drawdown of more than 90% from the paper peak.
For Maggiulli, examples like that show the core difficulty in crypto markets. High-risk strategies can work extremely well in a bull run, but success itself can make it harder for investors to stop using the same approach.
His measure of investment success is not whether someone made more than others in a single year. It is whether they can survive over the long run and eventually use their assets to live the life they want.
Younger investors should invest in earning power too
For younger people worried that they may be buying at all-time highs, Maggiulli said entry point is often overemphasized. Most younger investors still have limited capital, so even a near-term market setback is unlikely to destroy their finances in absolute terms.
Career development, income growth, and the ability to keep investing for decades matter far more to long-run wealth outcomes. He even said a weak market early in an investing life is not necessarily a bad thing. Lower prices allow younger investors to accumulate more units with future income. The more dangerous moment is a prolonged bear market close to retirement, when portfolio size is at its largest.
That fits another major idea in Just Keep Buying: when starting capital is small, raising income often matters more than squeezing out a few extra percentage points of return.
As he put it, if someone has only $1,000 to invest, even a 10% increase in return adds just $100. But improving earnings through job skills, entrepreneurship, or content creation can generate far more investable capital than stock picking alone.
Across the interview cited by ABMedia, Maggiulli’s answer to the “can I still buy stocks here” question was not a market call. It was a framework: define the purpose of the money and the time horizon first, then decide whether it belongs in cash and short-term government paper or in a diversified mix of long-term productive assets.