diff --git a/cache.js b/cache.js
index 719982b..039666e 100644
--- a/cache.js
+++ b/cache.js
@@ -37,6 +37,10 @@ export class CacheDict {
     async contains(chain, key) {
         return await redis.hExists(`${chain}|${this.series}`, key)
     }
+
+    async items(chain) {
+        return Object.entries(await redis.hGetAll(`${chain}|${this.series}`)).map(([k, v]) => [k, v === null ? null : '' + v])
+    }
 }
 
 
@@ -83,3 +87,4 @@ export const vaultOpenOrders = new CacheDict('voo')
 export const vaultRecentlyClosedOrders = new CacheDict('vrco')
 export const orderFilled = new CacheDict('of')
 export const ohlcs = new CacheDict('ohlc')
+export const marks = new CacheDict('mark.usd')
diff --git a/chain.js b/chain.js
index 9939694..cabfd0b 100644
--- a/chain.js
+++ b/chain.js
@@ -1,4 +1,15 @@
 import fs from "fs";
+import {marks} from "./cache.js";
 
 export const chainInfo = JSON.parse(fs.readFileSync('../contract/version.json')).chainInfo
 console.log('chainInfo', chainInfo)
+
+export async function joinChain( socket, chainId ) {
+    if (socket.chainId)
+        socket.leave(socket.chainId)
+    socket.join(chainId)
+    socket.chainId = chainId
+    const items = await marks.items(chainId);
+    for (let [token,mark] of items)
+        socket.emit('mark.usd', chainId, token, mark)
+}
diff --git a/route.js b/route.js
index a625f30..99f1c1a 100644
--- a/route.js
+++ b/route.js
@@ -4,6 +4,7 @@ import {requestVault, loginAddress} from "./vault.js";
 import {subOHLCs, subPools, unsubOHLCs, unsubPools} from "./pool.js";
 import {gib} from "./faucet.js";
 import {approveRegion, approveTOS} from "./approval.js";
+import {joinChain} from "./chain.js";
 
 // Server route handling
 
@@ -21,6 +22,7 @@ export function initIO() {
         socket.on('gib', async (chainId, owner, vault, tokenAmounts) => await gib(chainId, owner, vault, tokenAmounts))
         socket.on('approveTOS', (time, version, callback) => approveTOS(socket, time, version, callback))
         socket.on('approveRegion', (bypass) => approveRegion(socket, bypass))
+        socket.on('chain', async (chainId) => await joinChain(socket, chainId))
         socket.join('public')
     });
 }