stock market
Property
depends on a metric forgetton of factorsfor starters, how the forget did you get the first million?
Yeah this is the obvious choice. I'd probably even hire an professional investor to do it for me.
Idk like inherit it or something
if you play your cards REALLY right, depending on how you invest you might be able to get to 2 mil in 6 months, mabye more mabye less. the stock market is a minefield
if you inherited it then it's almost impossible to double 1 mil in a year unless you have major economical knowledge or huge talents and business knowledge combined.
Probably wouldn't double your money through that in a year