Probably just help verify that the stock market is a random walk with a meager trend upwards that doesn't beat inflation + trading costs.
That doesn't sound right. Let me clear that up for you. Since 1950:
S&P 500 Annual Price Change: 7.2%
S&P 500 Annual Div Dist: 3.6%
S&P 500 Annual Total Return: 11.0%
Annual Inflation: 3.8%
Annual Real Price Change: 3.3%
Annual Real Total Return: 7.0 %
One sample tells you nothing about randomness. What if you buy in August 1929? What if you hold for a more realistic 20 or 30 years from peak earning years to retirement?
Annual Total Return: 9.1%
Annual Real Total Return: 5.9%
Annual Total Return: 9.8%
Annual Real Total Return: 7.0%
If you're interested, here's a simulator that looks at historic market data. You'll note that even the lowest possible percentile of 30-year holding periods will still yield a 3.43% inflation-adjusted total return: https://dqydj.com/sp-500-historical-return-calculator-popout...
If not, look at http://www.macrotrends.net/1319/dow-jones-100-year-historica...
Let's buy in August 1929 at 5338.69, and sell 20 years later, in August 1949, at 1822.87 (inflation-adjusted). Congratulations, you lost two thirds of your money.
Sell 30 years later instead? August 1959, at 5525.23. Wow, after 30 years you're up almost 3.5%!
That assumes that the efficient-market hypothesis holds true, but it has yet to be thoroughly proven or disproven... (and funds like Medallion would strongly suggest otherwise for the medium term: https://www.bloomberg.com/news/articles/2016-11-21/how-renai...)
That's not to say returns are actually random, but in any given time range, it appears to be.
Or are you saying that movements aren't actually random, and only appear to be?