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The value and profit or loss (P/L) of your options positions are all calculated based on the mark price. The mark price is a reference price used to determine the fair value of an option.
There are two ways to find the mark price of an option:
Go to the option's quotes page.
Check the options chain.
Mark price calculation by options type:
| Options Type | Mark Price Calculation |
| US stock options and index options | Mark Price = (Best Bid + Best Ask) / 2 |
| Hong Kong stock option | Mark Price = Last Price, unless: • If Best Ask < Last Price, then Mark Price = Best Ask • If Best Bid > Last Price, then Mark Price = Best Bid |
US options are now connected to OCC (Options Clearing Corporation) settlement prices. After the US market closes (generally at 8:00 PM ET on trading days), we will update the market value of your US options positions using the official OCC settlement price
