The S&P 500 has closed at an all-time high on roughly 30% of all trading days since 1950. If you had refused to invest on any of those days, you would have been out of the market for nearly a third of your investing life, on average, and missed most of the long-term gains in the process.
That framing matters because "all-time high" sounds like a warning. It is not. It is just what a growing market looks like most of the time.
What the Research Actually Shows
In 2012, Vanguard published a study comparing lump-sum investing (put the money in now) against dollar-cost averaging (spread it out over 12 months) across U.S., U.K., and Australian markets going back to 1926. In the U.S., lump sum outperformed DCA in roughly 2 out of every 3 twelve-month periods. The result held across all three markets. The reason is simple: markets go up more often than they go down. Every day you hold cash waiting for a better entry, you are more likely losing ground than gaining it.
The Vanguard study's title was blunt: "Dollar-Cost Averaging Just Means Taking Risk Later." It is not a strategy for getting in cheaper. It is a strategy for managing anxiety at the cost of expected return.
The "Wait for a Dip" Math
Waiting for a 10% correction before investing feels disciplined. Run the numbers and it usually is not.
The table below shows two investors who each start with $10,000 in January. Investor A buys immediately. Investor B waits for a 10% pullback. The market rises 15% over the year before pulling back 10% in December.
| Investor | Strategy | Entry Point | Year-End Value | vs. Investor A |
|---|---|---|---|---|
| Investor A | Buy immediately (Jan) | Index at 100 | $11,350 | — |
| Investor B | Wait for 10% dip (Dec) | Index at 103.5 | $10,000 | -$1,350 |
Investor B got their 10% dip. They still underperformed by $1,350 because the market climbed 15% before the dip arrived, and they sat in cash the whole time. The dip took them from 115 back to 103.5, not back to 100. They bought higher than Investor A and missed 11 months of gains while waiting.
This scenario plays out more often than the one where patience is rewarded. The rewarded version requires the dip to arrive quickly and recover fully. That happens. It just happens less than half the time.
The One Exception Worth Taking Seriously
If your time horizon is under three years, this calculus changes. A 30% drawdown in year one of a three-year window is a real problem because you may not have time to recover before you need the money. In that case, putting everything in at once at an all-time high does carry meaningful risk, and spreading purchases over 6–12 months is a reasonable hedge.
For money you will not touch for a decade or longer, a near-term correction is noise. The S&P 500 has recovered from every drawdown in its history, including 2000–2002 (down 49%) and 2007–2009 (down 57%), and gone on to new all-time highs each time. The question for long-term investors is not "what if it drops?" but "will it be higher in 20 years than it is today?" The historical answer to that question is yes, regardless of what today's price is.
What This Looks Like in Practice
You have $20,000 to invest in a 3-fund portfolio or a broad index like VOO or VTI. The market is at an all-time high. The ETF BFF answer: invest it today, or within the next week. Do not split it into 12 monthly installments to feel better about the timing. Set a target allocation, buy it, and stop checking the price daily.
If $20,000 at once feels like too much exposure, a compromise that keeps most of the expected return intact: invest half now and the other half over the following two months. That gets you roughly 75% of lump-sum's expected return advantage while taking a meaningful amount of the anxiety off the table. More than two months and you start giving back most of the benefit.
The bigger risk for most people is not buying at 100 when the market briefly dips to 92. It is staying in cash at 100, watching the market hit 130, and finally buying at 125 after convincing yourself the run is real. That sequence plays out constantly and it is far more expensive than a suboptimal entry point.
Not sure what to actually buy? The 3-fund portfolio gives you the entire market in three ETFs.
Read the 3-Fund Portfolio Guide →The Short Version
- The S&P 500 has been at or near an all-time high for roughly 30% of all trading days since 1950. ATH is a normal market condition, not a danger signal.
- Vanguard's research found lump-sum investing beats 12-month dollar-cost averaging about 66% of the time in U.S. markets. The reason: markets trend up, so cash is the losing position on most days.
- Waiting for a dip requires the dip to arrive before the market climbs further. That happens less often than investors expect.
- For time horizons under three years, DCA over 6–12 months is a reasonable hedge against a poorly-timed large correction.
- For 10+ year time horizons, entry timing is close to irrelevant. Total return over a decade swamps any difference in entry price.
- The most expensive mistake is not buying at a high. It is staying out so long that you eventually buy at a higher one.