Is Matthew 24.40 the rapture

Yes, it is referring to the rapture.

Another Answer:

The term 'rapture' is not in the Scripture and is a tradition of men. The verse in Matthew is in reference to the 2nd Coming of Jesus to rule on Earth at the blast of the 7th Trumpet. It will be a loud and visible event where the firstfruits will rise from their graves or on the earth to meet their King in the sky. It will not be a secret or silent 'rapture' as some teach since the 19th century.