diff --git a/packages/social-controllers/CHANGELOG.md b/packages/social-controllers/CHANGELOG.md
index 58cde501931..10507ede569 100644
--- a/packages/social-controllers/CHANGELOG.md
+++ b/packages/social-controllers/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add optional `marketCap` to the `Trade` type (and `TradeStruct`) — historical token market cap at trade time from the social API ([#9605](https://github.com/MetaMask/core/pull/9605))
+
 ## [2.5.0]
 
 ### Added
diff --git a/packages/social-controllers/src/social-types.ts b/packages/social-controllers/src/social-types.ts
index 91d803e4672..3bf4b5b7880 100644
--- a/packages/social-controllers/src/social-types.ts
+++ b/packages/social-controllers/src/social-types.ts
@@ -50,6 +50,8 @@ export const TradeStruct = structType({
   perpLeverage: optional(nullable(number())),
   tokenAmount: number(),
   usdCost: number(),
+  /** Token market cap in USD at trade time. `null` when Clicker has no mark. */
+  marketCap: optional(nullable(number())),
   timestamp: number(),
   transactionHash: string(),
 });