The two main factors to the slippage are the delay of the execution for a position and market illiquidity during a certain period.
Slippage happens when the price you aim for is not the final execution price of a position. It can be caused by the following factors:
1) Market Volatility: Prices can fluctuate significantly based on the market condition. The expected price might be skipped.
2) Low Liquidity: If there are not many buyers or sellers willing to make trades, there might be few prices available.
3) Order Size: High trading volume/lots can cause the position to be executed in different market depths.
4) News Events and Economic Releases: Sudden news can cause prices to move fast, making it tough to trade at the intended price.
