diff --git a/trader/lighter_trader_v2.go b/trader/lighter_trader_v2.go
index 2b6b8588..febe6c17 100644
--- a/trader/lighter_trader_v2.go
+++ b/trader/lighter_trader_v2.go
@@ -99,6 +99,10 @@ func NewLighterTraderV2(walletAddr, apiKeyPrivateKeyHex string, apiKeyIndex int,
 		return nil, fmt.Errorf("wallet address is required")
 	}
 
+	// Convert to checksum address (Lighter API is case-sensitive)
+	walletAddr = ToChecksumAddress(walletAddr)
+	logger.Infof("Using checksum address: %s", walletAddr)
+
 	// 2. Validate API Key
 	if apiKeyPrivateKeyHex == "" {
 		return nil, fmt.Errorf("API Key private key is required")
diff --git a/trader/lighter_types.go b/trader/lighter_types.go
index c29e067b..55f9b4f5 100644
--- a/trader/lighter_types.go
+++ b/trader/lighter_types.go
@@ -1,6 +1,11 @@
 package trader
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+
+	"golang.org/x/crypto/sha3"
+)
 
 // AccountBalance Account balance information (Lighter)
 type AccountBalance struct {
@@ -79,3 +84,43 @@ func parseFloat(s string) (float64, error) {
 	_, err := fmt.Sscanf(s, "%f", &f)
 	return f, err
 }
+
+// ToChecksumAddress converts an Ethereum address to EIP-55 checksum format
+// This is required for Lighter API which is case-sensitive for addresses
+func ToChecksumAddress(address string) string {
+	// Remove 0x prefix and convert to lowercase
+	addr := strings.ToLower(strings.TrimPrefix(address, "0x"))
+	if len(addr) != 40 {
+		return address // Return original if invalid length
+	}
+
+	// Compute Keccak-256 hash of the lowercase address
+	hasher := sha3.NewLegacyKeccak256()
+	hasher.Write([]byte(addr))
+	hash := hasher.Sum(nil)
+
+	// Build checksum address
+	var result strings.Builder
+	result.WriteString("0x")
+
+	for i, c := range addr {
+		// Get the corresponding nibble from the hash
+		// Each byte in hash contains 2 nibbles (4 bits each)
+		hashByte := hash[i/2]
+		var nibble byte
+		if i%2 == 0 {
+			nibble = hashByte >> 4 // High nibble
+		} else {
+			nibble = hashByte & 0x0F // Low nibble
+		}
+
+		// If nibble >= 8, uppercase the character (if it's a letter)
+		if nibble >= 8 && c >= 'a' && c <= 'f' {
+			result.WriteByte(byte(c) - 32) // Convert to uppercase
+		} else {
+			result.WriteByte(byte(c))
+		}
+	}
+
+	return result.String()
+}