diff --git a/__tests__/utils.test.ts b/__tests__/utils.test.ts
new file mode 100644
index 0000000..443a6c5
--- /dev/null
+++ b/__tests__/utils.test.ts
@@ -0,0 +1,204 @@
+import { describe, it, expect } from 'vitest';
+import {
+    formatSymbolForTradingView,
+    formatMarketCapValue,
+    formatChangePercent,
+    getChangeColorClass,
+    calculateNewsDistribution,
+} from '@/lib/utils';
+
+describe('formatSymbolForTradingView', () => {
+    it('returns empty string for empty input', () => {
+        expect(formatSymbolForTradingView('')).toBe('');
+    });
+
+    it('returns uppercase US symbol as-is', () => {
+        expect(formatSymbolForTradingView('AAPL')).toBe('AAPL');
+        expect(formatSymbolForTradingView('aapl')).toBe('AAPL');
+    });
+
+    // Asia-Pacific exchanges
+    it('maps Taiwan (.TW) to TWSE prefix', () => {
+        expect(formatSymbolForTradingView('2330.TW')).toBe('TWSE:2330');
+    });
+
+    it('maps Taiwan OTC (.TWO) to TPEX prefix', () => {
+        expect(formatSymbolForTradingView('6488.TWO')).toBe('TPEX:6488');
+    });
+
+    it('maps Tokyo (.T) to TSE prefix', () => {
+        expect(formatSymbolForTradingView('7203.T')).toBe('TSE:7203');
+    });
+
+    it('maps Hong Kong (.HK) to HKEX prefix', () => {
+        expect(formatSymbolForTradingView('0700.HK')).toBe('HKEX:0700');
+    });
+
+    it('maps Shanghai (.SS) to SSE prefix', () => {
+        expect(formatSymbolForTradingView('600519.SS')).toBe('SSE:600519');
+    });
+
+    it('maps Shenzhen (.SZ) to SZSE prefix', () => {
+        expect(formatSymbolForTradingView('000858.SZ')).toBe('SZSE:000858');
+    });
+
+    it('maps Korea (.KS) to KRX prefix', () => {
+        expect(formatSymbolForTradingView('005930.KS')).toBe('KRX:005930');
+    });
+
+    it('maps India NSE (.NS) to NSE prefix', () => {
+        expect(formatSymbolForTradingView('RELIANCE.NS')).toBe('NSE:RELIANCE');
+    });
+
+    it('maps India BSE (.BO) to BSE prefix', () => {
+        expect(formatSymbolForTradingView('RELIANCE.BO')).toBe('BSE:RELIANCE');
+    });
+
+    it('maps Australia (.AX) to ASX prefix', () => {
+        expect(formatSymbolForTradingView('BHP.AX')).toBe('ASX:BHP');
+    });
+
+    it('maps Singapore (.SI) to SGX prefix', () => {
+        expect(formatSymbolForTradingView('D05.SI')).toBe('SGX:D05');
+    });
+
+    // European exchanges
+    it('maps London (.L) to LSE prefix', () => {
+        expect(formatSymbolForTradingView('SHEL.L')).toBe('LSE:SHEL');
+    });
+
+    it('maps Germany/Xetra (.DE) to XETR prefix', () => {
+        expect(formatSymbolForTradingView('SAP.DE')).toBe('XETR:SAP');
+    });
+
+    it('maps Paris (.PA) to EURONEXT prefix', () => {
+        expect(formatSymbolForTradingView('MC.PA')).toBe('EURONEXT:MC');
+    });
+
+    it('maps Amsterdam (.AS) to EURONEXT prefix', () => {
+        expect(formatSymbolForTradingView('ASML.AS')).toBe('EURONEXT:ASML');
+    });
+
+    it('maps Milan (.MI) to MIL prefix', () => {
+        expect(formatSymbolForTradingView('ENI.MI')).toBe('MIL:ENI');
+    });
+
+    it('maps Madrid (.MC) to BME prefix', () => {
+        expect(formatSymbolForTradingView('SAN.MC')).toBe('BME:SAN');
+    });
+
+    it('maps Swiss (.SW) to SIX prefix', () => {
+        expect(formatSymbolForTradingView('NESN.SW')).toBe('SIX:NESN');
+    });
+
+    it('maps Stockholm (.ST) to OMXSTO prefix', () => {
+        expect(formatSymbolForTradingView('ERIC-B.ST')).toBe('OMXSTO:ERIC-B');
+    });
+
+    // Americas
+    it('maps Toronto (.TO) to TSX prefix', () => {
+        expect(formatSymbolForTradingView('RY.TO')).toBe('TSX:RY');
+    });
+
+    it('maps Brazil (.SA) to BMFBOVESPA prefix', () => {
+        expect(formatSymbolForTradingView('VALE3.SA')).toBe('BMFBOVESPA:VALE3');
+    });
+
+    // Middle East & Africa
+    it('maps Tel Aviv (.TA) to TASE prefix', () => {
+        expect(formatSymbolForTradingView('TEVA.TA')).toBe('TASE:TEVA');
+    });
+
+    it('maps Johannesburg (.JO) to JSE prefix', () => {
+        expect(formatSymbolForTradingView('NPN.JO')).toBe('JSE:NPN');
+    });
+
+    // Case insensitivity
+    it('handles lowercase input', () => {
+        expect(formatSymbolForTradingView('2330.tw')).toBe('TWSE:2330');
+        expect(formatSymbolForTradingView('shel.l')).toBe('LSE:SHEL');
+    });
+
+    // Longer suffix matched before shorter (.TWO before .TW)
+    it('prioritizes longer suffixes over shorter ones', () => {
+        // .TWO should match before .TW
+        expect(formatSymbolForTradingView('6488.TWO')).toBe('TPEX:6488');
+        // But .TW still works for regular TW symbols
+        expect(formatSymbolForTradingView('2330.TW')).toBe('TWSE:2330');
+    });
+});
+
+describe('formatMarketCapValue', () => {
+    it('returns N/A for invalid inputs', () => {
+        expect(formatMarketCapValue(0)).toBe('N/A');
+        expect(formatMarketCapValue(-100)).toBe('N/A');
+        expect(formatMarketCapValue(NaN)).toBe('N/A');
+        expect(formatMarketCapValue(Infinity)).toBe('N/A');
+    });
+
+    it('formats trillions', () => {
+        expect(formatMarketCapValue(3.1e12)).toBe('$3.10T');
+    });
+
+    it('formats billions', () => {
+        expect(formatMarketCapValue(900e9)).toBe('$900.00B');
+    });
+
+    it('formats millions', () => {
+        expect(formatMarketCapValue(25e6)).toBe('$25.00M');
+    });
+
+    it('formats sub-million values', () => {
+        expect(formatMarketCapValue(999999.99)).toBe('$999999.99');
+    });
+});
+
+describe('formatChangePercent', () => {
+    it('returns empty string for undefined/null', () => {
+        expect(formatChangePercent(undefined)).toBe('');
+        expect(formatChangePercent(null as any)).toBe('');
+    });
+
+    it('formats positive change with + sign', () => {
+        expect(formatChangePercent(2.5)).toBe('+2.50%');
+    });
+
+    it('formats negative change', () => {
+        expect(formatChangePercent(-1.23)).toBe('-1.23%');
+    });
+
+    it('formats zero change', () => {
+        expect(formatChangePercent(0)).toBe('0.00%');
+    });
+});
+
+describe('getChangeColorClass', () => {
+    it('returns gray for zero or undefined', () => {
+        expect(getChangeColorClass(0)).toBe('text-gray-400');
+        expect(getChangeColorClass(undefined)).toBe('text-gray-400');
+    });
+
+    it('returns green for positive', () => {
+        expect(getChangeColorClass(1.5)).toBe('text-green-500');
+    });
+
+    it('returns red for negative', () => {
+        expect(getChangeColorClass(-0.5)).toBe('text-red-500');
+    });
+});
+
+describe('calculateNewsDistribution', () => {
+    it('returns 3 items per symbol for 1-2 symbols', () => {
+        expect(calculateNewsDistribution(1).itemsPerSymbol).toBe(3);
+        expect(calculateNewsDistribution(2).itemsPerSymbol).toBe(3);
+    });
+
+    it('returns 2 items per symbol for exactly 3', () => {
+        expect(calculateNewsDistribution(3).itemsPerSymbol).toBe(2);
+    });
+
+    it('returns 1 item per symbol for 4+', () => {
+        expect(calculateNewsDistribution(5).itemsPerSymbol).toBe(1);
+        expect(calculateNewsDistribution(10).itemsPerSymbol).toBe(1);
+    });
+});
diff --git a/lib/utils.ts b/lib/utils.ts
index 183dab7..e910ae2 100644
--- a/lib/utils.ts
+++ b/lib/utils.ts
@@ -25,7 +25,7 @@ export function delay(ms: number) {
     return new Promise((resolve) => setTimeout(resolve, ms));
 }
 
-// Formatted string like "$3.10T", "$900.00B", "$25.00M" or "$999,999.99"
+// Formatted string like "$3.10T", "$900.00B", "$25.00M" or "$999999.99"
 export function formatMarketCapValue(marketCapUsd: number): string {
     if (!Number.isFinite(marketCapUsd) || marketCapUsd <= 0) return 'N/A';
 
@@ -154,24 +154,80 @@ export const getFormattedTodayDate = () => new Date().toLocaleDateString('en-US'
     timeZone: 'UTC',
 });
 
+/**
+ * Maps Finnhub exchange suffixes to TradingView exchange prefixes.
+ * Finnhub symbols use a dot-suffix convention (e.g. "2330.TW"),
+ * while TradingView uses a colon-prefix convention (e.g. "TWSE:2330").
+ */
+const FINNHUB_TO_TRADINGVIEW_EXCHANGE: Record<string, string> = {
+    // Asia-Pacific
+    '.TW': 'TWSE',   // Taiwan Stock Exchange
+    '.TWO': 'TPEX',  // Taiwan OTC Exchange
+    '.T': 'TSE',     // Tokyo Stock Exchange
+    '.HK': 'HKEX',   // Hong Kong
+    '.SS': 'SSE',    // Shanghai
+    '.SZ': 'SZSE',   // Shenzhen
+    '.KS': 'KRX',    // Korea Exchange
+    '.KQ': 'KRX',    // KOSDAQ (Korea)
+    '.SI': 'SGX',    // Singapore
+    '.AX': 'ASX',    // Australian Securities Exchange
+    '.NZ': 'NZX',    // New Zealand
+    '.BO': 'BSE',    // Bombay Stock Exchange
+    '.NS': 'NSE',    // National Stock Exchange of India
+    '.BK': 'SET',    // Stock Exchange of Thailand
+    '.JK': 'IDX',    // Indonesia Stock Exchange
+    '.KL': 'MYX',    // Bursa Malaysia
+
+    // Europe
+    '.L': 'LSE',     // London Stock Exchange
+    '.IL': 'LSE',    // London (IOB international)
+    '.DE': 'XETR',   // Deutsche Boerse (Xetra)
+    '.F': 'FWB',     // Frankfurt Stock Exchange
+    '.PA': 'EURONEXT', // Euronext Paris
+    '.AS': 'EURONEXT', // Euronext Amsterdam
+    '.BR': 'EURONEXT', // Euronext Brussels
+    '.LS': 'EURONEXT', // Euronext Lisbon
+    '.MI': 'MIL',    // Borsa Italiana (Milan)
+    '.MC': 'BME',    // Bolsa de Madrid
+    '.ST': 'OMXSTO', // Stockholm (Nasdaq Nordic)
+    '.HE': 'OMXHEX', // Helsinki (Nasdaq Nordic)
+    '.CO': 'OMXCOP', // Copenhagen (Nasdaq Nordic)
+    '.OL': 'OSL',    // Oslo Stock Exchange
+    '.SW': 'SIX',    // SIX Swiss Exchange
+    '.VI': 'VIE',    // Vienna Stock Exchange
+    '.WA': 'GPW',    // Warsaw Stock Exchange
+    '.PR': 'PSE',    // Prague Stock Exchange
+    '.AT': 'ATHEX',  // Athens Stock Exchange
+    '.IS': 'BIST',   // Borsa Istanbul
+
+    // Americas
+    '.TO': 'TSX',    // Toronto Stock Exchange
+    '.V': 'TSXV',    // TSX Venture Exchange
+    '.SA': 'BMFBOVESPA', // B3 (Brazil)
+    '.MX': 'BMV',    // Bolsa Mexicana de Valores
+    '.BA': 'BCBA',   // Buenos Aires Stock Exchange
+
+    // Middle East & Africa
+    '.TA': 'TASE',   // Tel Aviv Stock Exchange
+    '.JO': 'JSE',    // Johannesburg Stock Exchange
+};
+
 export function formatSymbolForTradingView(symbol: string): string {
     if (!symbol) return '';
     const upperSymbol = symbol.toUpperCase();
-    
-    // Shanghai
-    if (upperSymbol.endsWith('.SS')) {
-        return `SSE:${upperSymbol.slice(0, -3)}`;
+
+    // Check for known exchange suffixes, trying longer suffixes first
+    // to avoid ".TWO" matching ".TW" prematurely
+    const suffixes = Object.keys(FINNHUB_TO_TRADINGVIEW_EXCHANGE)
+        .sort((a, b) => b.length - a.length);
+
+    for (const suffix of suffixes) {
+        if (upperSymbol.endsWith(suffix.toUpperCase())) {
+            const ticker = upperSymbol.slice(0, -suffix.length);
+            const exchange = FINNHUB_TO_TRADINGVIEW_EXCHANGE[suffix];
+            return `${exchange}:${ticker}`;
+        }
     }
-    
-    // Shenzhen
-    if (upperSymbol.endsWith('.SZ')) {
-        return `SZSE:${upperSymbol.slice(0, -3)}`;
-    }
-    
-    // Hong Kong
-    if (upperSymbol.endsWith('.HK')) {
-        return `HKEX:${upperSymbol.slice(0, -3)}`;
-    }
-    
+
     return upperSymbol;
 }
\ No newline at end of file