It's at $102 now according to the social club, maybe $117 was the time to sell this time round.
I think last time PIS was rising it dropped a bit then carried on climbing, if it's another save game, i'd just leave it there and see what happens. I think it took maybe a week or two to get to $300 last time round.
Double check from the game though as the amounts don't always match, i think the social club is an hour or two behind the game.
Keep an eye on it and buy in with everything next time it's at rock bottom $1-$2 on a separate save game.
If i sell now @ $102, Michael has gone from 100 mill to 8.6 billion since the 15th, the other two are similar.
I'll probably cash out tonight and buy all the properties, i'm only at about 70% of Career i think.