An analyst widely known on smartlab writes on the same smartlab:
Yes, and before I heard such a theory that it is necessary to buy shares of the same volume from each salary every month, and then no price drops will be scary, because in the long run the profit will flow like a river and everything will be in chocolate.
This theory looks like, certainly, mysteriously, since it is rather difficult to verify — ten years must pass, least, to understand that there are no miracles here, because they just don't exist. But in such cases, a ghostly hope arises, especially after a long string of failures, what is this, really, the only way to succeed. And a person begins to believe in this because for him this is the last chance, since no other strategies work anymore., and he clings to this saving straw — Buy the same amount every month" — and a bright future will be assured.
I have long wanted to test this strategy on history, but not in the usual way to test it, since there is no initial deposit and it is constantly replenished over time, in connection with which there are difficulties in determining the average annual percentage of profit. But today, finally, decided to tackle this closely. Was, everything is simple — in Excel spreadsheets, there is a special function for this case and it is called XIRR. That's why, backtest technology suggests itself:
1. Writing a script in a backtesting program — something like `` we buy at the beginning of each month for a certain fixed amount"
2. We copy the data of transactions with their value and dates into a spreadsheet.
3. Calculate the remainder (deposit) from all deposited money to date.
4. Using the XIRR function.
That's all. As a result, we get the average annual percentage of profit(loss) for the tested number of years.
If we take specifically Gazprom, it for 10 recent years loss -5% per annum. For 5 recent years loss -6% per annum. And no money rain. So hopes are crushed :)
Some more results — MICEX index for 10 years +5,50% (in rubles, certainly). The same American dollar analogue of RSX (Russian ETEF) -4,5% per annum.
SPY +10% annual against 5% per annum if you just buy and hold.
QQQ +16.5% annual against 10% per annum if you buy and hold.
All in all, it seems that the profitability of this approach approximately repeats the profitability of the tested asset itself, well, maybe with slight deviations. If stock growing, then profitability also grows, if the stock falls, and the profitability will be the same negative. I.e, cash flow is canceled out of nowhere :)
Fragment of the application of the XIRR function for Gazprom in the last 5 years:
