Limit up and limit down levels for a particular stock are determined by stock exchanges and regulatory bodies. These levels are designed to prevent excessive volatility in the market and protect investors from sudden, sharp price movements. The levels are set based on a percentage change from the previous day's closing price of the stock.

For example, if the limit up a level is set at 10%, it means that trading in the stock will be halted if its price rises by 10% or more from the previous day's closing price. Similarly, if the limit down level is set at 10%, trading will be halted if the price falls by 10% or more from the previous day's closing price.

Limit up and limit down levels can be adjusted by stock exchanges and regulatory bodies as needed to reflect changes in market conditions. It's important for investors to be aware of these levels and understand how they can impact trading in a particular stock.

Limit up and limit down levels are price boundaries set to prevent excessive volatility in a stock within a trading session. These limits are determined by regulatory bodies like the Securities and Exchange Commission (SEC) in the U.S. or exchanges themselves.

For a particular stock, these levels are typically based on a percentage of the stock's average price over a recent period. In U.S. markets, the Limit Up-Limit Down (LULD) mechanism applies bands that restrict trading when a stock’s price fluctuates too drastically. For example, if a stock’s price moves outside a predetermined range (e.g., 5% or 10%), trading can be paused temporarily. The limits are adjusted according to the stock's price tier, market capitalization, and overall liquidity.