When does SPX500 actually rise?

Every hour below is a real measurement: how often SPX500 closed higher than it opened in that hour of the week, across 39,343 hourly bars. Not signals — base rates, with the sample size on every figure.

When does SPX500 actually move?

We cannot demonstrate which way SPX500 leans in any hour — that is the caveat above, and it is honest. How far it moves is a different question, and this one it answers.

A typical hour in SPX500 ends up 3.5 pts from where it opened — and covers rather more than that on the way, since a move out and part-way back still finishes near its start. Every figure in this section is that net distance; its quietest (Monday 04:00) moves 1.7. The spread on a round trip is about 0.7, so the gap between the busiest hour and the quietest one is the difference between a move worth paying for and one that is mostly cost.

Does the London–New York overlap actually deliver?

Ask when to trade anything and you get the same answer everywhere: the London–New York overlap, 12:00–16:00 UTC. Those pages do cite numbers — the overlap is roughly 19% of the day and carries over a third of daily volume, and spreads there are genuinely the tightest. Every one of those is a figure about how busy the hour is. None is a figure about which way it goes. So here is that number for SPX500, from 39,343 hourly bars:

The gap is 0.6 percentage points — inside what chance produces at these sample sizes. On direction alone, the overlap is not a better bet for SPX500 than the rest of the day. That does not make the advice useless: the overlap is where liquidity and spreads are best, which matters for cost. It just is not an edge in which way price closes.

Sessions overlap by design, so these windows share bars.

The strongest and weakest hours

Averaged across the trading week, the hour that has leaned up hardest is 18:00 UTC — SPX500 closed higher 54.3% of 1,671 times there, though that lean is thinner than it looks. The weakest is 21:00 UTC, closing higher only 46.3% of 551 times.

Hour × weekday, the whole picture

Colour is the up-rate — red leaned down, teal leaned up. The brass dot marks buckets whose lean is statistically beyond chance at |z|≥3. Most cells have no dot. That is the honest shape of the market: mostly noise, with a few stubborn corners.

No single weekday-hour bucket of SPX500 clears the |z|≥3 bar. That is a finding, not a failure — most markets, most of the time, are indistinguishable from chance at this resolution.

Days and seasons

Monday has been the friendliest day (54.0% of 7,766), Tuesday the least (50.7%). By calendar month, November leads at 52.9% and December trails at 50.5% — month buckets carry roughly a twelfth of the sample each, so hold them more loosely than the hourly figures.

Did any of it survive a real backtest?

Colours are description. A different question is whether a simple rule built on them — enter at the open of a bucket, exit at its close, pay a realistic spread — would have made money, and kept making it after a realistic spread is charged. We ran that test across 4,248 rules on the whole board: 200 finished net positive — 4.7%.

No published rule runs on SPX500 once spread costs are charged. The strategy board shows that too — a leaderboard that only shows winners is lying by omission.

Watch it live

These are the same numbers, updating as each hour begins — free to embed on your own site from the widget builder:

Read it without fooling yourself

• The percentage is the headline, not the story. 54.3% from 1,671 samples is information; the same figure from 40 samples is noise. Every number here carries its n.
• The dots matter more than the colours. A vivid cell with no dot is well inside what chance produces.
• Direction is free; getting paid is not. A reliable lean smaller than your spread costs more than it earns.
• These are frequencies, not forecasts. 5 years of "usually" contains every kind of "except when".

The guide walks through all four traps with live numbers.

Where SPX500 sits

Two things worth knowing before you treat any of the above as SPX500-specific.

These markets keep almost the same clock

Correlating the shape of the trading day — each hour's distance from that market's own average hour — against every other market we hold:

• GER40 (DAX) — +0.79 — almost the same schedule. Holding both is close to one position at twice the size, not two edges.
• NAS100 — +0.75 — almost the same schedule. Holding both is close to one position at twice the size, not two edges.
• UK100 (FTSE) — +0.69 — a good deal of shape in common.

Tested claims that land differently here

Of the 21 pieces of timing folklore we tested across all markets, these are the ones where SPX500 itself moves beyond chance:

• Tuesday volatility runs 120-130% of Monday.
  SPX500: 50.7% in the window against 54.0% outside it, on 7,976 candles — z = -4.1.
• Never trade Monday — the market is still waking up from the weekend.
  SPX500: 54.0% in the window against 51.8% outside it, on 7,766 candles — z = 3.5.
• Tuesday to Thursday are the most active, trending days.
  SPX500: 51.7% in the window against 53.0% outside it, on 23,807 candles — z = -2.6.

What we have tested that covers SPX500

Each of these is a claim this industry sells, measured against a control. ⚠ Only the ones whose measurement actually included SPX500 are listed — several of our tests exclude markets outright, and offering one here that skipped this symbol would be the opposite of the point.

• Do weekend gaps fill?
  "Gaps fill 90% of the time" is true and empty — a matched midweek move fills just as often. The indices do the opposite.
• Does the first hour set the day?
  A green first hour tells you the first hour was green. Not one of 17 markets reaches even a weak significance bar.
• Does a hot streak mean anything?
  A streak is as predictive at four weeks' lag as at one. Memory decays; drift does not — which is why there is no streak feature on this site.
• Does yesterday's high or low matter?
  68,762 breaks across 19 markets. The level holds 50.4% of the time — slightly less than an arbitrary level the same distance away.

All three blocks are computed from the same files this page is, so they cannot drift from it. The full picture — every market against every hour, with the noise count attached — is on the screener, and the tests behind the significance bar are on /evidence.

Open SPX500's strongest hour in the dashboard →