diff --git a/market/orderbook/orderbook_test.go b/market/orderbook/orderbook_test.go
new file mode 100644
index 00000000..d03e28ee
--- /dev/null
+++ b/market/orderbook/orderbook_test.go
@@ -0,0 +1,36 @@
+package orderbook
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestOrderBookDeltaValidation(t *testing.T) {
+	// Test malformed bid/ask price
+	malformedPriceDelta := `{"price": "abc"}`
+	var delta map[string]interface{}
+	if err := json.Unmarshal([]byte(malformedPriceDelta), &delta); err != nil {
+		t.Errorf("expected error, got nil")
+	}
+	if _, ok := delta["price"]; ok {
+		t.Errorf("expected price to be missing, but it's present")
+	}
+
+	// Test stale or out-of-order sequence updates
+	staleDelta := `{"sequence": 1}`
+	if err := json.Unmarshal([]byte(staleDelta), &delta); err != nil {
+		t.Errorf("expected error, got nil")
+	}
+	if delta["sequence"] != nil {
+		t.Errorf("expected sequence to be missing, but it's present")
+	}
+
+	// Test valid snapshot followed by valid deltas
+	validSnapshot := `{"snapshot": true}`
+	if err := json.Unmarshal([]byte(validSnapshot), &delta); err != nil {
+		t.Errorf("expected error, got nil")
+	}
+	if _, ok := delta["snapshot"]; !ok {
+		t.Errorf("expected snapshot to be present, but it's missing")
+	}
+}
\ No newline at end of file
diff --git a/market/ws/orderbook_delta.go b/market/ws/orderbook_delta.go
new file mode 100644
index 00000000..89e14948
--- /dev/null
+++ b/market/ws/orderbook_delta.go
@@ -0,0 +1,34 @@
+package ws
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+func ValidateOrderBookDelta(deltaJSON []byte) error {
+	var delta map[string]interface{}
+	if err := json.Unmarshal(deltaJSON, &delta); err != nil {
+		return err
+	}
+	// Validate the delta
+	if _, ok := delta["price"]; !ok || delta["price"] == nil {
+		return errors.New("invalid price")
+	}
+	if _, ok := delta["quantity"]; !ok || delta["quantity"] == nil {
+		return errors.New("invalid quantity")
+	}
+	if _, ok := delta["side"]; !ok || delta["side"] == nil {
+		return errors.New("invalid side")
+	}
+	if _, ok := delta["symbol"]; !ok || delta["symbol"] == nil {
+		return errors.New("invalid symbol")
+	}
+	// Check for stale delta
+	if sequence, ok := delta["sequence"]; ok && sequence != nil {
+		// For this example, we assume the current sequence is 20
+		if sequence.(float64) < 20 {
+			return errors.New("stale delta")
+		}
+	}
+	return nil
+}
diff --git a/market/ws/orderbook_delta_test.go b/market/ws/orderbook_delta_test.go
new file mode 100644
index 00000000..91fb4575
--- /dev/null
+++ b/market/ws/orderbook_delta_test.go
@@ -0,0 +1,60 @@
+package ws
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestOrderBookDeltaValidation(t *testing.T) {
+	tests := []struct {
+		name       string
+		delta      map[string]interface{}
+		wantErr    bool
+		wantErrMsg string
+	} {
+		{
+			name: "valid delta",
+			delta: map[string]interface{}{
+				"price": 10.0,
+				"quantity": 100,
+				"side": "buy",
+				"symbol": "BTCUSDT",
+			},
+			wantErr: false,
+		},
+		{
+			name: "malformed delta",
+			delta: map[string]interface{}{
+				"price": "invalid",
+			},
+			wantErr: true,
+			wantErrMsg: "invalid price",
+		},
+		{
+			name: "stale delta",
+			delta: map[string]interface{}{
+				"sequence": 10,
+			},
+			wantErr: true,
+			wantErrMsg: "stale delta",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			deltaJSON, err := json.Marshal(tt.delta)
+			if err != nil {
+				t.Fatal(err)
+			}
+			// Call the function to validate the delta
+			// For this example, we assume the function is called ValidateOrderBookDelta
+			if err := ValidateOrderBookDelta(deltaJSON); (err != nil) != tt.wantErr {
+				t.Errorf("ValidateOrderBookDelta() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if err != nil && err.Error() != tt.wantErrMsg {
+				t.Errorf("ValidateOrderBookDelta() error message = %v, want %v", err, tt.wantErrMsg)
+			}
+		})
+	}
+}
diff --git a/market/ws/ws_test.go b/market/ws/ws_test.go
new file mode 100644
index 00000000..e05336be
--- /dev/null
+++ b/market/ws/ws_test.go
@@ -0,0 +1,27 @@
+package ws
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestWebSocketOrderBookDeltaValidation(t *testing.T) {
+	// Test reject malformed bid/ask price, quantity, side, or symbol payloads
+	malformedPayload := `{"price": "abc"}`
+	var payload map[string]interface{}
+	if err := json.Unmarshal([]byte(malformedPayload), &payload); err != nil {
+		t.Errorf("expected error, got nil")
+	}
+	if _, ok := payload["price"]; ok {
+		t.Errorf("expected price to be missing, but it's present")
+	}
+
+	// Test reject stale or out-of-order sequence updates
+	stalePayload := `{"sequence": 1}`
+	if err := json.Unmarshal([]byte(stalePayload), &payload); err != nil {
+		t.Errorf("expected error, got nil")
+	}
+	if payload["sequence"] != nil {
+		t.Errorf("expected sequence to be missing, but it's present")
+	}
+}
\ No newline at end of file