99 preflop SB vs BTN

My completely uneducated opinion says you call here. I do like the 3bet though.

You can probably fold tbh because people dont 4b enough. Definitely not jamming unless I know the person is capable of bluffing enough.

Three betting from the SB is fine. A 3 bet or fold strategy from the SB is a pretty standard one, and 99 is too strong to fold to a button raise. If I’m doing the math right you have to call 12.5BB to win a 36.5 BB pot (your 11.5BB three bet + villains 24BB 4! + 1BB from BB). To break even you therefore need about 25.5% equity. Against even a very tight 4! range of AK, JJ+ you have 33% equity. That would give us enough to call, except we don’t realize all our equity. It probably is a pretty close decision. If villain is four betting a wider range then it probably is a call. If villain isn’t four betting AK it’s a fold.

I would overfold. If he's good enough to bluff 4b he'll be putting max pressure post so we're regging out oop with no advantages I can see (assuming they aren't good enough to X back enough when we call). This may well be jam vs very competent players and aggro fish but need more proof and ideally showdowns i would think

And if he is exploiting us with 4b i'd rather call more IP as a counter and wrangle it out from there. doesn't 4b stat take forever to converge anyway?

yeah 300 hands wont show you anything about how he's 4betting

I was actually looking at this spot with TT and I'm still not sure, folding 99 here is fine

I'd be surprised if regs are finding Ajo,KQo, QTs, A9s

A shove is okay against opponents with a high 4bet range stat like 6%+.
But micro pool 4bet and fold to 5bet less than GTO (4bet range ~4.5% and fold to 5bet ~40%), so I would choose between calling and folding w/o reads.

Thanks for the answers! It confirms I did a mistake here (but I got lucky)

€0.20 NL (5 max)

BB: 188.25 BB
UTG: 157.15 BB
CO: 115.4 BB
BTN: 101.5 BB
Hero (SB): 117.5 BB

Hero posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has 9♦ 9♣

fold, fold, BTN raises to 2.5 BB, Hero raises to 11.5 BB, fold, BTN raises to 24 BB, Hero raises to 117.5 BB and is all-in, BTN calls 77.5 BB and is all-in

Flop: (204 BB, 2 players) K♠ 9♥ 6♣

Turn: (204 BB, 2 players) 2♦

River: (204 BB, 2 players) 4♣

BTN shows J♠ J♥ (One Pair, Jacks)
Hero shows 9♦ 9♣ (Three of a Kind, Nines)
Hero wins 208.25 BB

I've heard this before, it hasn't sunk in. So formula is roughly: larger 4b = widen jam range/fold calling range?

You call less fold more and jam more.

gracias