I didn’t use a real monkey but I ran this experiment myself over 2015/2018 as a ‘Monkey Stocks League’, with 23 participants picking 5 random stocks for their portfolios (though only a few used actual real money to buy their stocks (from FTSE 350), as opposed to ‘virtual’ money).
@Jim_mcgrain might remember when we pulled the stocks randomly out of a hat in a pub in York? 
The winning randomly picked portfolio showed a gain of 60% (9.38%) after year 1, 106% (17.68%) after 2 years and 141% (19.95%) after 3 years.
The numbers in brackets is the FTSE 350 Total Return for the respective periods.
Of course, not all random stocks made profits but 78% of the portfolios did.