diff --git a/apps/backend/src/modules/portfolio/portfolio.controller.ts b/apps/backend/src/modules/portfolio/portfolio.controller.ts
index 777a1d5..9632fe6 100644
--- a/apps/backend/src/modules/portfolio/portfolio.controller.ts
+++ b/apps/backend/src/modules/portfolio/portfolio.controller.ts
@@ -27,7 +27,7 @@ const nullDataEnvelopeSchema = {
   type: 'object',
   properties: {
     data: {
-      nullable: true,
+      type: 'null',
     },
     meta: {
       $ref: getSchemaPath(PortfolioResponseMetaDto),
diff --git a/apps/backend/src/openapi-artifacts.spec.ts b/apps/backend/src/openapi-artifacts.spec.ts
index 52529a5..9a7a962 100644
--- a/apps/backend/src/openapi-artifacts.spec.ts
+++ b/apps/backend/src/openapi-artifacts.spec.ts
@@ -93,4 +93,16 @@ describe('checked-in OpenAPI artifacts', () => {
       ).toBeDefined();
     }
   });
+
+  it('portfolio delete operations document a null data envelope', () => {
+    for (const [method, path, status] of [
+      ['delete', '/api/v1/portfolios/{id}', 200],
+      ['delete', '/api/v1/portfolios/{id}/positions/{positionId}', 200],
+    ] as const) {
+      expect(
+        openapi.paths[path][method].responses[status].content['application/json'].schema.properties
+          .data,
+      ).toMatchObject({ type: 'null' });
+    }
+  });
 });
diff --git a/apps/frontend/src/api/types.ts b/apps/frontend/src/api/types.ts
index 9d9d3e2..0046607 100644
--- a/apps/frontend/src/api/types.ts
+++ b/apps/frontend/src/api/types.ts
@@ -1171,7 +1171,7 @@ export interface operations {
         };
         content: {
           'application/json': {
-            data: unknown;
+            data: null;
             meta: components['schemas']['PortfolioResponseMetaDto'];
           };
         };
@@ -1246,7 +1246,7 @@ export interface operations {
         };
         content: {
           'application/json': {
-            data: unknown;
+            data: null;
             meta: components['schemas']['PortfolioResponseMetaDto'];
           };
         };
diff --git a/docs/openapi/openapi.yaml b/docs/openapi/openapi.yaml
index e122902..767391b 100644
--- a/docs/openapi/openapi.yaml
+++ b/docs/openapi/openapi.yaml
@@ -586,7 +586,7 @@ paths:
                 type: object
                 properties:
                   data:
-                    nullable: true
+                    type: 'null'
                   meta:
                     $ref: '#/components/schemas/PortfolioResponseMetaDto'
                 required:
@@ -678,7 +678,7 @@ paths:
                 type: object
                 properties:
                   data:
-                    nullable: true
+                    type: 'null'
                   meta:
                     $ref: '#/components/schemas/PortfolioResponseMetaDto'
                 required: