diff --git a/lib/actions/activity-actions.js b/lib/actions/activity-actions.js
index 201b249a1..ce77fd9d0 100644
--- a/lib/actions/activity-actions.js
+++ b/lib/actions/activity-actions.js
@@ -1,112 +1,161 @@
 // @flow
 
+import invariant from 'invariant';
+import * as React from 'react';
+
 import {
   extractKeyserverIDFromID,
   extractKeyserverIDFromIDOptional,
 } from '../keyserver-conn/keyserver-call-utils.js';
 import { useKeyserverCall } from '../keyserver-conn/keyserver-call.js';
 import type { CallKeyserverEndpoint } from '../keyserver-conn/keyserver-conn-types.js';
+import type { OutboundDMOperationSpecification } from '../shared/dm-ops/dm-op-utils.js';
+import { dmOperationSpecificationTypes } from '../shared/dm-ops/dm-op-utils.js';
+import { useProcessAndSendDMOperation } from '../shared/dm-ops/process-dm-ops.js';
 import type {
   ActivityUpdate,
   ActivityUpdateSuccessPayload,
   SetThreadUnreadStatusPayload,
   SetThreadUnreadStatusRequest,
 } from '../types/activity-types.js';
+import type { DMChangeThreadReadStatusOperation } from '../types/dm-ops.js';
+import type { ThreadInfo } from '../types/minimally-encoded-thread-permissions-types';
+import { threadTypeIsThick } from '../types/thread-types-enum.js';
+import { useSelector } from '../utils/redux-utils.js';
 
 export type UpdateActivityInput = {
   +activityUpdates: $ReadOnlyArray<ActivityUpdate>,
 };
 
 const updateActivityActionTypes = Object.freeze({
   started: 'UPDATE_ACTIVITY_STARTED',
   success: 'UPDATE_ACTIVITY_SUCCESS',
   failed: 'UPDATE_ACTIVITY_FAILED',
 });
 const updateActivity =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((input: UpdateActivityInput) => Promise<ActivityUpdateSuccessPayload>) =>
   async input => {
     const { activityUpdates } = input;
     const requests: { [string]: { +updates: ActivityUpdate[] } } = {};
     for (const update of activityUpdates) {
       const optionalKeyserverID = extractKeyserverIDFromIDOptional(
         update.threadID,
       );
       if (!optionalKeyserverID) {
         continue;
       }
       const keyserverID: string = optionalKeyserverID;
       if (!requests[keyserverID]) {
         requests[keyserverID] = { updates: [] };
       }
       requests[keyserverID].updates.push(update);
     }
 
     const responses = await callKeyserverEndpoint('update_activity', requests);
 
     let unfocusedToUnread: $ReadOnlyArray<string> = [];
     for (const keyserverID in responses) {
       unfocusedToUnread = unfocusedToUnread.concat(
         responses[keyserverID].unfocusedToUnread,
       );
     }
 
     const sortedActivityUpdates: {
       [keyserverID: string]: $ReadOnlyArray<ActivityUpdate>,
     } = {};
     for (const keyserverID in requests) {
       sortedActivityUpdates[keyserverID] = requests[keyserverID].updates;
     }
 
     return {
       activityUpdates: sortedActivityUpdates,
       result: {
         unfocusedToUnread,
       },
     };
   };
 
 function useUpdateActivity(): (
   input: UpdateActivityInput,
 ) => Promise<ActivityUpdateSuccessPayload> {
   return useKeyserverCall(updateActivity);
 }
 
 const setThreadUnreadStatusActionTypes = Object.freeze({
   started: 'SET_THREAD_UNREAD_STATUS_STARTED',
   success: 'SET_THREAD_UNREAD_STATUS_SUCCESS',
   failed: 'SET_THREAD_UNREAD_STATUS_FAILED',
 });
 const setThreadUnreadStatus =
   (
     callKeyserverEndpoint: CallKeyserverEndpoint,
   ): ((
     input: SetThreadUnreadStatusRequest,
   ) => Promise<SetThreadUnreadStatusPayload>) =>
   async input => {
     const keyserverID = extractKeyserverIDFromID(input.threadID);
     const requests = { [keyserverID]: input };
 
     const responses = await callKeyserverEndpoint(
       'set_thread_unread_status',
       requests,
     );
     return {
       resetToUnread: responses[keyserverID].resetToUnread,
       threadID: input.threadID,
     };
   };
 
-function useSetThreadUnreadStatus(): (
+function useSetThreadUnreadStatus(
+  threadInfo: ThreadInfo,
+): (
   request: SetThreadUnreadStatusRequest,
 ) => Promise<SetThreadUnreadStatusPayload> {
-  return useKeyserverCall(setThreadUnreadStatus);
+  const viewerID = useSelector(
+    state => state.currentUserInfo && state.currentUserInfo.id,
+  );
+  const processAndSendDMOperation = useProcessAndSendDMOperation();
+  const keyserverCall = useKeyserverCall(setThreadUnreadStatus);
+
+  return React.useCallback(
+    async (input: SetThreadUnreadStatusRequest) => {
+      if (!threadTypeIsThick(threadInfo.type)) {
+        return await keyserverCall(input);
+      }
+
+      invariant(viewerID, 'viewerID must be set');
+      const op: DMChangeThreadReadStatusOperation = {
+        type: 'change_thread_read_status',
+        time: Date.now(),
+        threadID: threadInfo.id,
+        creatorID: viewerID,
+        unread: !threadInfo.currentUser.unread,
+      };
+
+      const opSpecification: OutboundDMOperationSpecification = {
+        type: dmOperationSpecificationTypes.OUTBOUND,
+        op,
+        recipients: {
+          type: 'self_devices',
+        },
+      };
+
+      await processAndSendDMOperation(opSpecification);
+      return {
+        resetToUnread: false,
+        threadID: threadInfo.id,
+      };
+    },
+
+    [keyserverCall, threadInfo, viewerID, processAndSendDMOperation],
+  );
 }
 
 export {
   updateActivityActionTypes,
   useUpdateActivity,
   setThreadUnreadStatusActionTypes,
   useSetThreadUnreadStatus,
 };
diff --git a/lib/hooks/toggle-unread-status.js b/lib/hooks/toggle-unread-status.js
index f9378e00b..24de6c4cc 100644
--- a/lib/hooks/toggle-unread-status.js
+++ b/lib/hooks/toggle-unread-status.js
@@ -1,54 +1,56 @@
 // @flow
 
 import * as React from 'react';
 
 import {
   setThreadUnreadStatusActionTypes,
   useSetThreadUnreadStatus,
 } from '../actions/activity-actions.js';
 import type {
   SetThreadUnreadStatusPayload,
   SetThreadUnreadStatusRequest,
 } from '../types/activity-types.js';
 import type { ThreadInfo } from '../types/minimally-encoded-thread-permissions-types.js';
 import { useDispatchActionPromise } from '../utils/redux-promise-utils.js';
 
 function useToggleUnreadStatus(
   threadInfo: ThreadInfo,
   mostRecentNonLocalMessage: ?string,
   afterAction: () => void,
 ): () => void {
   const dispatchActionPromise = useDispatchActionPromise();
   const { currentUser } = threadInfo;
   const boundSetThreadUnreadStatus: (
     request: SetThreadUnreadStatusRequest,
-  ) => Promise<SetThreadUnreadStatusPayload> = useSetThreadUnreadStatus();
+  ) => Promise<SetThreadUnreadStatusPayload> =
+    useSetThreadUnreadStatus(threadInfo);
+
   const toggleUnreadStatus = React.useCallback(() => {
     const request = {
       threadID: threadInfo.id,
       unread: !currentUser.unread,
       latestMessage: mostRecentNonLocalMessage,
     };
     void dispatchActionPromise(
       setThreadUnreadStatusActionTypes,
       boundSetThreadUnreadStatus(request),
       undefined,
       ({
         threadID: threadInfo.id,
         unread: !currentUser.unread,
       }: { +threadID: string, +unread: boolean }),
     );
     afterAction();
   }, [
-    threadInfo.id,
+    threadInfo,
     currentUser.unread,
     mostRecentNonLocalMessage,
     dispatchActionPromise,
     afterAction,
     boundSetThreadUnreadStatus,
   ]);
 
   return toggleUnreadStatus;
 }
 
 export default useToggleUnreadStatus;