Momentum Trading Strategy in S&P 500 (Day Trading System Explained)

This article presents a last-hour trading strategy. This is in practice a momentum strategy.

Here is the hypothesis: if SPY rallies from the open until the last hour, can we make money by going long one hour before the close and exiting on the close? This is a “last hour” trading strategy:

The momentum day trading strategy in the S&P 500 – long

Previously I have written about the different periods of the trading day:

This is a strategy I have traded live over the last year (just a few trades). I have tested with different thresholds, but it seems like the more SPY is up from the open (it works better from the open than from yesterday’s close), the more likely to rally the last hour.


I have used a threshold of 1.25% from open to the last hour, and I get 18 fills from 2010 until the present and 13 winners. This is an average of .39% per fill, not bad for such a short holding period.

Considering a total holding period of 18 hours over more than 2.5 years, a total gain of 7% must be considered extraordinary.

Here is the equity curve:

There are few fills, though. Increasing the threshold to 1.5%, we get 8 fills and 6 winners, and the average increases to 0.49%.

I don’t get such remarkable results if I measure from yesterday’s close to the last hour. I’m not sure why. Does anyone of the readers have any suggestions?

It’s still good, but the average drops. Here are the results from yesterday’s close to last hour:

Threshold P/L #fills #wins Avg
1.25 7.41 66 40 0.11
1.5 4.89 42 23 0.12
1.75 5.53 29 19 0.19
2 4.07 21 14 0.19
2.5 3.89 12 10 0.32
3 1 4 2 0.25

The momentum day trading strategy in the S&P 500 – short

To reverse it, ie. to go short if a large drop from the open, does also work (see below for explanation).

There seems to be a tendency downwards for small movements, but large drops get reversed.

However, measuring from close until the last hour, my results are a bit disappointing. Using the open, I get tradeable results using a threshold of about 1.5%, but 1.75% seems better (the more movement, the better). Here is the equity curve for 1.75% (15 fills, eight winners):

Why does this strategy work? I have no idea except for the following:

  • Short covering, or
  • rebalancing in ETFs

There are a lot of traders who fade SPY. If SPY just continues higher, a lot of them might want to take a stop-loss by covering and thus needs to buy (and they may take profits on big down days and buy during the last hour).

The other reason is the growth in leveraged ETFs. A lot of the leveraged ETFs need to rebalance every day, pushing more fuel to the fire.

When the market goes up, leveraged bull ETFs need to buy more to keep the leverage ratio. When the market drops, it’s the opposite effect because bear ETFs need to buy.

According to academic research papers, as much as 10-50% of the MOC orders could be attributed to these ETFs!

In another article, we looked at the return during the last hour of trading. The trading edges are small, but this article shows there are possibilities to find market inefficiencies. There are several ways to go about to inefficiencies in the markets.

However, day trading is hard and we believe overnight strategies are easier prey to hunt for.


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– What is the last-hour trading strategy in the S&P 500, and how does it work?

The last-hour trading strategy is a momentum-based strategy where traders buy or sell S&P 500 (SPY) one hour before the market’s closing and exit on the close. The strategy is based on capitalizing on momentum trends in the market during the last hour of trading.

– Why does the Momentum Trading Strategy In S&P 500 the yield better results when measured from the market open rather than from yesterday’s close?

The strategy appears to yield better results when measured from the market open because it focuses on capturing momentum and trends that develop within the trading day. Measuring from the open helps traders benefit from intraday movements.

– What are the academic research findings regarding MOC (Market on Close) orders and ETFs?

Academic research suggests that a significant portion (10-50%) of MOC orders can be attributed to ETFs, particularly leveraged ETFs. These ETFs play a role in market inefficiencies during the closing hours.

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