Investing Bankroll

[Bet_to_Nguyen]

What kind of bankroll is needed to invest in individual stocks where transactions may take place every couple of weeks or so?

In poker, more profit percentage is taken away at 3/6 ($3 rake) vs. 100/200 ($3 rake). In other words, is $10k in an Ameritrade, etc. account the equivalent of playing 5/10 on Party Poker? That is type of answer I'm after if that makes any sense.