<p>A circuit breaker in the stock market is a temporary halt in trading designed to cool down extreme price <a href="/NewSite/encyclopedia/volatility/" class="ency-link">volatility</a>. It's a safety mechanism triggered when an asset's price moves rapidly in a short period, either up or down.</p>

<h2>How It Works</h2>
<p>Circuit breakers are activated when the price of an asset moves beyond certain thresholds within a specific time frame. These thresholds are typically set at 10%, 20%, and 30% for individual stocks, and 7% for the S&P 500 index. Here's how they work:</p>
<ul>
  <li><strong>Level 1 (10%):</strong> Trading is halted for 15 minutes.</li>
  <li><strong>Level 2 (20%):</strong> Trading is halted for 15 minutes.</li>
  <li><strong>Level 3 (30%):</strong> Trading is halted for the rest of the day.</li>
</ul>
<p>These levels and time frames can vary depending on the exchange and the asset being traded.</p>

<h2>Why It Matters</h2>
<p>Circuit breakers matter because they help prevent panic selling or buying that can lead to market crashes. They provide a cooling-off period during which investors can reassess their positions and make more informed decisions. For instance, during the "Flash Crash" of 2010, the Dow Jones Industrial Average dropped over 1000 points in just a few minutes. If circuit breakers had been in place, this rapid decline could have been halted, potentially preventing significant losses for investors.</p>