SB 3-Bet vs CO 4-Bet
CO 4-bet to 19.8 bb. Jam or call with the top of your 3-bet range; fold the bluffs.
Hands at a glance
All-in (20% of hands)
Always: AA, AKs, KK. Sometimes: A5s (30%), A4s (20%), AKo (70%), QQ (50%).
Call (15% of hands)
Sometimes: AQs (80%), AJs (30%), AKo (30%), KQs (40%), QQ (50%), JJ (80%), TT (50%), 99 (20%).
Each square is a starting hand: pairs on the diagonal, suited hands above it, offsuit below. A square split in two colors is a mix: play it each way that often.
How to play it
You 3-bet a Cutoff open from the Small Blind, and the Cutoff 4-bets. Your 3-betting range here is 11% of all starting hands (the colored squares). Go all-in with 20% of it, call 15% and fold the other 65%.
A Cutoff opens a wide range, so your 3-bet range here is wider and holds bluffs: suited aces and other hands that block the 4-bettor's strongest holdings. Those bluffs fold to the 4-bet, which is why so much of the range folds.
Facing the same 4-bet from the CO: the BTN folds 44%, the BB folds 34%.
Related charts: SB vs CO Open, CO Open vs SB 3-Bet, CO Open Range.