The Stock Market Works by Day, but It Loves the Night

Mine started on 1/29/1993 and stopped on 5/21/2019. I think our results agreed.

IMHO, it is much more profitable just buy and hold SPY - the real free lunch without effort.

Sure just buy Monday morning, and will compare in a couple of years. Your buying after a 10 year bull market and SPY up almost 20% YTD. I guess if you have a decade or two your buy and hold may work.
 
Sure just buy Monday morning, and will compare in a couple of years. Your buying after a 10 year bull market and SPY up almost 20% YTD. I guess if you have a decade or two your buy and hold may work.

I think the point they are making is what I have been saying all along. Buying at cash close and selling at cash open the next day works great in a 10 year bull market. Then you get a blip like, I dunno', Feb 2018, Oct 2018, and May 2019.

That kinda' messes up yer mojo.

And what happens when we get a 5 year stair-step down 30% or 40% or whatever?

And you never answered the question...Where'd you vanish to after Oct 2018 reared it's ugly head?

It is not risk free, man.
 
I downloaded historical SPY from Yahoo Finance going all the way back to 1993. Backtested buying one share at close and selling back that share at open the next day. After 25 years, I netted 0% profit, not counting commissions and slippages.

To be exact:

Total cost of purchase: $788,966.24,

Total receipt of sale: $788,983.23.

Total profits: $16.99.

What am I missing? Where is the free lunch?
Using yahoo finance SPY prices adjusted for splits and dividends buying a single share at the close (starting Jan 29, 1993), selling at the next day's open (last sell July 11, 2019) without accounting for slippage or commissions, some statistics were:
numValues 6659
sum 273.537898999999
min -9.54807600000001
max 5.866806
mean 0.0410779244631325
sampleStdDev 0.696582829813863
median 0.0391690000000011
medianAbsDev 0.253011000000001
skewness -0.884340196556304
excessKurtosis 16.3349982402817
>Thresh_0_Pct 56.21


It backtested profitably, but an average profit of 4.1 cents per share might have been consumed by slippage and commissions.

Buying a single share at the close on Jan 29, 1993 and selling at the open on July 11, 2019 using the adjusted prices would have resulted in a profit of 272.613250 or a compounded annual growth of 9.57 percent.
This is really interesting. Your backtesting seems to show the exact opposite results of what the article claims. So in basic theory, the inverse operation should be successful. You should be able to see large gains by buying at the open and selling at the close everyday.

Did you use regular market hours in your backtesting? (Premarket & after hours may skew the results.)
 
This is really interesting. Your backtesting seems to show the exact opposite results of what the article claims. So in basic theory, the inverse operation should be successful. You should be able to see large gains by buying at the open and selling at the close everyday.

Did you use regular market hours in your backtesting? (Premarket & after hours may skew the results.)

From 2005 until today (12th of July 2019) it looks like this (3453 full trading sessions):

upload_2019-7-13_11-19-46.png


The Open is simply the difference between the cash close at 16:00 and the open the next day at 09:30. ES futures.

So, yes, unsurprisingly there is a skew towards a positive open price, but less than you might expect. 45 % of days did in fact open negatively.

I also did a check on the other claim from the article and posted my findings in another thread a little while back. I found that my results did not equal the claims from the article.

Adding in a filter, i.e., buying the cash close after a strong down day might yield better returns. Just buying the cash close and selling the open does not seem like a robust strategy to me. I certainly wouldn't trade it.
 
This is really interesting. Your backtesting seems to show the exact opposite results of what the article claims. So in basic theory, the inverse operation should be successful. You should be able to see large gains by buying at the open and selling at the close everyday.

Did you use regular market hours in your backtesting? (Premarket & after hours may skew the results.)
Regular.
 
This is really interesting. Your backtesting seems to show the exact opposite results of what the article claims. So in basic theory, the inverse operation should be successful. You should be able to see large gains by buying at the open and selling at the close everyday.

Did you use regular market hours in your backtesting? (Premarket & after hours may skew the results.)

Your backtesting seems to show the exact opposite results of what the article claims.

Using yahoo data adjusted for dividends and splits but ignoring transaction costs, buying one share of SPY at the open (regular trading hours) and selling at the close (regular trading hours) from January 29, 1993 through July 11, 2019 results in:

numValues 6660
sum -0.9536529999998
min -10.092755
max 10.116016
mean -0.000143191141141111
sampleStdDev 1.02499980228868
median 0.0298219999999993
medianAbsDev 0.417475499999998
skewness -0.538117835395494
excessKurtosis 11.2369003505817
>Thresh_0_Pct 51.79


This more-or-less agrees with the original article's "not counting dividends ... buying the E.T.F. at the first second of regular trading every morning at 9:30 a.m. and selling at the 4 p.m. close ... down 4.4 percent since 1993" because the data I used was adjusted for dividends.

So I think the original article's premise is correct if there are no transaction costs.
 
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