Warrants - In the money, at the money and out of the money

A warrant is described as in-the-money (ITM), at-the-money (ATM) or out-of-the-money (OTM), depending on the relationship between its strike price and its underlying price.

A call warrant is OTM when its strike price is higher than its underlying price.

It is ITM, when its strike price is lower than its underlying price.

The situation is just the opposite for put warrants.

When its strike price is higher than its underlying price, a put warrant is ITM; and when its strike price is lower than its underlying price, it is OTM.

No matter it is a call or put, if the strike price is equal to the underlying price, the warrant is said to be ATM.


Summary

Call Warrant

ITM Strike Price < Underlying Price
ATM  Strike Price = Underlying Price
OTM  Strike Price > Underlying Price

Put Warrant

ITM   Strike Price > Underlying Price
ATM  Strike Price = Underlying Price
OTM  Strike Price < Underlying Price



Additional Notes

Call Warrant
An investor can buy a call warrant if he is optimistic about the outlook for its underlying.
When the underlying price does go above the strike price, in theory, the investor can exercise the warrant to buy the underlying at the strike price.
Then he can sell it in the market to earn the difference.
In practice, warrants are traded on a cash settlement basis, and investors will be paid the difference directly.

Put Warrant
In the case of a put warrant, an investor can go for it when he is pessimistic about the market outlook.
If the underlying price is lower than the strike price, in theory, the invstor can exercise the warrant and buy the underlying from the market for delivery to the issuer at the strike price to earn the difference.
In reality, investors will be paid the difference directly.
If it turns out that the underlying price is higher than the strike price, the investor will lose the cost of the warrant.

(The above assumes that the investor will hold the warrant until maturity.  Indeed, investors can also "buy low, sell high", and trade warrants just like stocks.)