Negative doubles after an overcall vary according to the suit opened and the suit overcalled.

After a minor-suit opening, negative doubles can be played thru four hearts, bringing spades into the picture.

SPECIAL DOUBLES

Negative thrufour heartsover a minor

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After a heart opening, negative doubles should be played thru three clubs, bringing diamonds and spades into the picture and staying below 3NT.

After a spade opening, negative doubles should be played thru three clubs, bringing diamonds and hearts into the picture and staying below 3NT.

After a major-suit opening, the thrump double has more value after anovercall of three diamond or after an overcall of three of the other major.

SPECIAL DOUBLES

Negative thru three clubs over a major
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1♥ (3♦/ 3♠ ) x=asking for stopper

1♠(3♦/ 3♥) x=asking for stopper

The thrump double: Do you want partner bidding the other major or four clubs when all you may need is a stopper in their suit?