Mark to Market (MTM) Calculator
Calculate mark-to-market value and unrealized gain or loss on any position.
Enter purchase price, current price, and shares or units to see paper P&L.
Mark to market (MTM) is the accounting practice of valuing a position at its current market price rather than what you originally paid. The difference is your unrealized gain or loss — real in economic terms, but not yet taxable because you have not sold.
The calculation:
Unrealized P&L = (Current Price - Purchase Price) x Shares
If you bought 500 shares at $40 and they now trade at $55, your unrealized gain is $7,500. If the price fell to $32, you are sitting on a $4,000 unrealized loss.
The term comes from futures markets, where the exchange marks open positions to market at the end of every trading day and settles the difference in cash immediately — a process called daily settlement. If your futures position moves against you by $2,000 overnight, $2,000 is debited from your margin account that evening, regardless of whether you placed any new trade. This is what makes futures different from stocks: you can lose money on a position you never touched that day.
For equities and bonds, brokerages show MTM as an informational number. It becomes real only when you sell and realize the gain or loss.
Tax note: unrealized gains are generally not taxable in most jurisdictions until realized. Some exceptions exist for certain derivatives, wash-sale violations, and mark-to-market elections available to professional traders under IRS Section 475.
Return on investment context: divide the unrealized P&L by the original cost to see your percentage gain or loss. This number, combined with how long you have held the position, gives you the annualized return — a better comparison than the raw dollar figure when you hold positions of different sizes.