Halftime in the market — what now?
By the end of June, we hit the statistical halftime: the first half (H1) is done, and the second half of the year (H2, July through December) begins. Investors often ask whether this means a quiet summer lull — or the big year-end rally. The data answers with a surprising split: on average, H2 looks unremarkable, yet inside it hides one of the most reliable seasonal patterns there is.
The citable headline number first: the fourth quarter closed positive in 79 % of all years for the S&P 500 since 1970 (44 of 56 years), and for the DAX in 89 % of years since 1988 (34 of 38). But before that sits the weakest quarter of the year. It is exactly this contrast that makes H2 so interesting.
What "second half of the year" means statistically
We split the trading year into two halves:
- H1 = January through June
- H2 = July through December
And H2 itself into two quarters:
- Q3 = July, August, September (the classic summer phase)
- Q4 = October, November, December (the "year-end season")
We measure the average return and the win rate (share of years with a positive result). The data is the S&P 500 (^GSPC) since 1970 — 56 complete years — and the DAX performance index (^GDAXI) since trading began in 1988.
One note up front: seasonality describes recurring patterns of the past, not a guarantee for the future. It shows where the market historically had a tailwind or headwind — not what happens tomorrow.
The average is misleading: H2 is split
At first glance the second half looks solid and uneventful. For the S&P 500, H2 gained +4.4 % on average; for the DAX +4.2 % — barely different from each index's first half. Stop here and you miss the real point.
Because this average is made of two very unequal phases: a flat-to-weak summer quarter and a powerful closing quarter. This table makes the break visible:
| Period | S&P 500 avg | S&P win rate | DAX avg | DAX win rate |
|---|---|---|---|---|
| Q3 (Jul–Sep) | +0.4 % | 62 % | −2.1 % | 47 % |
| Q4 (Oct–Dec) | +4.1 % | 79 % | +6.9 % | 89 % |
| H2 total | +4.4 % | 70 % | +4.2 % | 68 % |
The spread is most extreme for the DAX: the third quarter is negative on average (−2.1 %) and succeeds in barely half of all years — while the fourth quarter, at +6.9 % with an 89 % win rate, is by far the strongest and most reliable quarter of the entire trading year.
The weak Q3: the "summer doldrums"
The term "summer doldrums" describes the seasonal summer lull. It has a clear culprit in the monthly cycle: September. It is the historically weakest calendar month of the year for both the S&P 500 and the DAX.
The chart below shows the average return per calendar month for the S&P 500 over the past 30 years — the current month is highlighted:
Strong July, weak September
Within Q3, the seasonal path is anything but even:
- July is solid: +1.0 % on average for the S&P 500 with a 55 % win rate, +1.6 % for the DAX with 66 %. The summer usually starts friendly.
- August is mixed: near zero for the S&P 500, clearly negative for the DAX (−1.9 %).
- September is the weak spot: −0.8 % for the S&P 500 and −2.0 % for the DAX, with the lowest win rate of any month (45 % and 40 % respectively).
So the summer lull is less a continuous downtrend than a friendly start that fades in the second half of the quarter. That is why "stocks fall in summer" is too crude a rule of thumb — the data paints a more precise picture.
The strong Q4: one of the most reliable seasonal phases
After the September weakness, the picture turns. October, November and December together form the statistically best phase of the year. For the DAX, the consistency is especially remarkable:
- October: +2.0 %, 68 % win rate
- November: +2.6 %, 66 %
- December: +2.2 %, 74 %
Strung together, that produces a fourth quarter that closed positive in 34 of 38 years. For the S&P 500 the pattern is a touch milder but just as robust: 44 of 56 Q4 periods in the green, with a median of +5.5 %.
The DAX monthly cycle over 38 years shows the same path — the September dip and the year-end strength right next to each other:
Why these patterns emerge
Seasonal effects are not magic. Plausible, recurring drivers sit behind the H2 path — even if none of them is a law of nature:
- Liquidity and holiday season: Trading volume and attention are lower in summer. Thin markets react more sharply to negative news — that favours the August/September weakness.
- Portfolio reporting dates: Many institutional investors and funds tidy up their books at quarter-end. Year-end "window dressing" can support Q4 demand.
- Year-end effects: Bonus inflows, fresh pension allocations and the psychological "year-end optimism" historically fall in Q4 — phenomena like the "Santa Claus rally" belong here.
- Expectations: When many participants expect a year-end rally, that expectation can become partly self-fulfilling.
These drivers explain why the pattern stays remarkably stable across decades — but also why it can fail completely in individual years when a driver disappears or a shock intervenes.
Limits and counterexamples
Seasonality is a probabilistic context, not a signal. Three caveats are crucial:
- Averages hide dispersion. The +6.9 % in the DAX Q4 is a mean of strong gains and a few deep loss years. In 2008, for instance, the fourth quarter fell massively in the middle of the financial crisis — the pattern offered no protection.
- Exogenous shocks override seasonality at any time. A rate decision, a geopolitical event or a trade conflict can break any seasonal pattern. We saw this recently with the Sell-in-May effect in 2026, where a trade-deal rally overrode the typical summer weakness.
- Even a strong Q4 is never certain. In roughly one year in five (S&P 500) or one in ten (DAX), the fourth quarter closed negative. Confusing "reliable" with "guaranteed" misreads the statistics.
What investors should take from this — and what not
The second half of the year offers no roadmap, but valuable context for your own sense of timing:
- For long-term investors, the psychological framing is most useful. If the market feels sluggish in August/September, that is historically normal — no reason for hasty selling. The fourth quarter has, in the past, more than made up for the summer weakness.
- For active traders, the asymmetry is interesting: Q3 and Q4 have completely different risk/reward profiles, with win rates of 47 % and 89 % (DAX). Those who use seasonality typically combine it with further filters — such as technical indicators or the risk regime.
You can explore the interactive monthly cycle and the seasonal yearly cycle for any ticker on SeasonAlpha. To follow the summer phase actively, the sector rotation shows which sectors historically held up more defensively in weaker phases, and the risk cycle shows the current market regime.
Methodology & transparency
We calculate with normalized returns based on adjusted closing prices — not absolute index points. Quarterly and half-year figures are compounded from the monthly returns; the win rate counts the share of positive periods. How we check data and compute seasonality is laid out openly on our methodology page. The full risk notice is in the legal section.
Conclusion
The second half of the year is not an even path but a tale of two halves: a flat-to-weak third quarter — driven by September weakness — followed by one of the most reliable quarters of the trading year. The fourth quarter closed positive in 79 % of years for the S&P 500 and 89 % for the DAX. That is no promise, but a strong context. Find the interactive monthly cycle for any ticker on seasonalpha.ai.
Frequently Asked Questions
Is the second half of the year stronger or weaker for stocks?
On average, H2 is similar in strength to the first half (S&P 500 +4.4 %, DAX +4.2 %). What matters is the internal split: a weak third quarter and a markedly stronger fourth quarter.
Which quarter is historically the best?
The fourth quarter (October through December). For the DAX it closed positive in 89 % of years since 1988 (avg +6.9 %), and for the S&P 500 in 79 % of years since 1970 (median +5.5 %) — the most reliable quarter of both indices.
Why is September so weak?
September is the historically weakest calendar month for both the S&P 500 and the DAX. Explanations include lower summer liquidity, portfolio reshuffling after quarter-end reporting, and the heightened sensitivity of thin markets to negative news.
Can I rely on the Q4 rally?
No. A win rate of 79–89 % also means the fourth quarter was negative in one year in five to one in ten — such as 2008. Seasonality provides probabilities, not guarantees, and individual years can deviate sharply.