diff --git a/core/src/exchanges/hyperliquid/fetcher.ts b/core/src/exchanges/hyperliquid/fetcher.ts
index dc0bb47f..d2fcef84 100644
--- a/core/src/exchanges/hyperliquid/fetcher.ts
+++ b/core/src/exchanges/hyperliquid/fetcher.ts
@@ -66,6 +66,7 @@ export interface HyperliquidRawTrade {
     hash: string;    // transaction hash
     time: number;    // timestamp (ms)
     tid: number;     // trade id
+    users: string[]; // [takerAddress, makerAddress]
 }
 
 export interface HyperliquidRawMid {
@@ -87,6 +88,7 @@ export interface HyperliquidRawFill {
     fee: string;
     tid: number;
     feeToken: string;
+    builderFee?: string; // present when order was placed through a builder
 }
 
 export interface HyperliquidRawOpenOrder {
@@ -96,7 +98,7 @@ export interface HyperliquidRawOpenOrder {
     side: string;
     sz: string;
     timestamp: number;
-    origSz: string;
+    origSz?: string; // only returned by frontendOpenOrders, not openOrders
     cloid?: string;
 }
 
diff --git a/core/src/exchanges/hyperliquid/normalizer.ts b/core/src/exchanges/hyperliquid/normalizer.ts
index 255f688d..1fae240c 100644
--- a/core/src/exchanges/hyperliquid/normalizer.ts
+++ b/core/src/exchanges/hyperliquid/normalizer.ts
@@ -346,8 +346,9 @@ export class HyperliquidNormalizer implements IExchangeNormalizer<HyperliquidRaw
     }
 
     normalizeOpenOrder(raw: HyperliquidRawOpenOrder): Order {
-        const origSz = parseFloat(raw.origSz);
         const currentSz = parseFloat(raw.sz);
+        // origSz is only available from frontendOpenOrders; fall back to sz
+        const origSz = raw.origSz !== undefined ? parseFloat(raw.origSz) : currentSz;
 
         return {
             id: String(raw.oid),