<p>The <strong>VIX</strong> (<a href="/NewSite/encyclopedia/volatility/" class="ency-link">Volatility</a> Index) is a real‑time market gauge that reflects the market’s expectation of 30‑day volatility for the S&P&nbsp;500 index. Calculated from the prices of S&P&nbsp;500 index options, the VIX is often called the “fear index” because it tends to rise when investors anticipate larger price swings and fall when markets are calm.</p>

<h2>How It Works</h2>
<p>The VIX is derived from the implied volatility of a basket of S&P&nbsp;500 call and put options with near‑term expirations. By weighting these option prices, the formula estimates the annualized standard deviation of the index’s returns over the next 30 days, expressed as a percentage. A VIX reading of 20, for example, suggests the market expects the S&P&nbsp;500 to move about ±20% over the year, or roughly ±5.8% over a month. The index is updated continuously during trading hours and is disseminated by the Chicago Board Options Exchange (CBOE).</p>

<h2>Why It Matters</h2>
<p>Investors use the VIX to gauge market sentiment, hedge portfolios, and time volatility‑based strategies. For instance, during the March 2020 market turmoil, the VIX spiked above 80, signaling extreme fear and prompting many traders to buy VIX futures or options as a protective measure against further equity declines. Conversely, a persistently low VIX below 12 often indicates complacency, which can precede sudden market reversals. Understanding the VIX helps traders assess risk, allocate capital to volatility products, and interpret broader market conditions beyond pure price levels.</p>