diff --git a/packages/tracing/src/transaction.ts b/packages/tracing/src/transaction.ts
index 10435f5ecdb0..460e202b059c 100644
--- a/packages/tracing/src/transaction.ts
+++ b/packages/tracing/src/transaction.ts
@@ -42,7 +42,11 @@ export class Transaction extends SpanClass implements TransactionInterface {
 
     this._name = transactionContext.name || '';
 
-    this.metadata = transactionContext.metadata || {};
+    this.metadata = {
+      ...transactionContext.metadata,
+      spanMetadata: {},
+    };
+
     this._trimEnd = transactionContext.trimEnd;
 
     // this is because transactions are also spans, and spans have a transaction pointer
@@ -89,7 +93,7 @@ export class Transaction extends SpanClass implements TransactionInterface {
   /**
    * @inheritDoc
    */
-  public setMetadata(newMetadata: TransactionMetadata): void {
+  public setMetadata(newMetadata: Partial<TransactionMetadata>): void {
     this.metadata = { ...this.metadata, ...newMetadata };
   }
 
diff --git a/packages/types/src/transaction.ts b/packages/types/src/transaction.ts
index c60ae3d12cd1..d8029c2184cb 100644
--- a/packages/types/src/transaction.ts
+++ b/packages/types/src/transaction.ts
@@ -27,7 +27,7 @@ export interface TransactionContext extends SpanContext {
   /**
    * Metadata associated with the transaction, for internal SDK use.
    */
-  metadata?: TransactionMetadata;
+  metadata?: Partial<TransactionMetadata>;
 }
 
 /**
@@ -93,7 +93,7 @@ export interface Transaction extends TransactionContext, Span {
    * Set metadata for this transaction.
    * @hidden
    */
-  setMetadata(newMetadata: TransactionMetadata): void;
+  setMetadata(newMetadata: Partial<TransactionMetadata>): void;
 
   /** return the baggage for dynamic sampling and trace propagation */
   getBaggage(): Baggage;
@@ -147,6 +147,9 @@ export interface TransactionMetadata {
 
   /** Information on how a transaction name was generated. */
   source?: TransactionSource;
+
+  /** Metadata for the transaction's spans, keyed by spanId */
+  spanMetadata: { [spanId: string]: { [key: string]: unknown } };
 }
 
 /**