This is based on after-hours trading, where Alphabet is up 9%+ after an earnings...

tinkerrr on Feb 1, 2016 | parent | context | favorite | on: Alphabet Becomes the Most Valuable Public Company ...

This is based on after-hours trading, where Alphabet is up 9%+ after an earnings beat. The marketcap that you see in Google Finance is calculated based on the price at the end of the trading day, not after-hours trading.