diff --git a/modules/bitgo/test/v2/unit/wallet.ts b/modules/bitgo/test/v2/unit/wallet.ts
index 761fb25056..efccead059 100644
--- a/modules/bitgo/test/v2/unit/wallet.ts
+++ b/modules/bitgo/test/v2/unit/wallet.ts
@@ -21,6 +21,7 @@ import {
   ManageUnspentsOptions,
   MessageStandardType,
   MessageTypes,
+  NeedUserSignupError,
   PopulatedIntent,
   PrebuildTransactionOptions,
   PrebuildTransactionWithIntentOptions,
@@ -1994,6 +1995,48 @@ describe('V2 Wallet:', function () {
       createShareNock.isDone().should.be.True();
     });
 
+    it('should throw NeedUserSignupError when recipient pubkey is missing and spend permission is requested', async function () {
+      const userId = '456';
+      const email = 'newuser@sdktest.com';
+      const permissions = 'view,spend';
+      const walletPassphrase = 'bitgo1234';
+
+      // Simulate a user who has not yet logged in / set up their ECDH key
+      const getSharingKeyNock = nock(bgUrl)
+        .post('/api/v1/user/sharingkey', { email })
+        .reply(200, { userId });
+
+      await wallet
+        .shareWallet({ email, permissions, walletPassphrase })
+        .should.be.rejectedWith(NeedUserSignupError);
+
+      getSharingKeyNock.isDone().should.be.True();
+    });
+
+    it('should not throw NeedUserSignupError when recipient pubkey is missing but spend permission is not requested', async function () {
+      const userId = '456';
+      const email = 'newuser@sdktest.com';
+      const permissions = 'view';
+
+      // Sharing key without pubkey is fine for view-only shares
+      const getSharingKeyNock = nock(bgUrl)
+        .post('/api/v1/user/sharingkey', { email })
+        .reply(200, { userId });
+
+      const createShareNock = nock(bgUrl)
+        .post(`/api/v2/tbtc/wallet/${wallet.id()}/share`, {
+          user: userId,
+          permissions,
+          skipKeychain: true,
+        })
+        .reply(200, {});
+
+      await wallet.shareWallet({ email, permissions });
+
+      getSharingKeyNock.isDone().should.be.True();
+      createShareNock.isDone().should.be.True();
+    });
+
     describe('Hot Wallet Sharing', function () {
       const userId = '123';
       const email = 'shareto@sdktest.com';
diff --git a/modules/sdk-core/src/bitgo/wallet/wallet.ts b/modules/sdk-core/src/bitgo/wallet/wallet.ts
index a8c1952cf5..59bc1b39ab 100644
--- a/modules/sdk-core/src/bitgo/wallet/wallet.ts
+++ b/modules/sdk-core/src/bitgo/wallet/wallet.ts
@@ -2064,6 +2064,9 @@ export class Wallet implements IWallet {
     })) as any;
     let sharedKeychain;
     if (needsKeychain) {
+      if (!sharing.pubkey) {
+        throw new NeedUserSignupError(sharing.userId);
+      }
       sharedKeychain = await this.prepareSharedKeychain(
         params.walletPassphrase,
         sharing.pubkey,