The public market capitalization of Google parent Alphabet topped the $1 trillion mark shortly before the close of trading on Thursday, making it the fourth S&P 500 component to top that level.

Only two other U.S. names are past the threshold: Apple, valued at about $1.38 trillion, and Microsoft, at $1.27 trillion. Globally, the list is topped by Saudi Aramco, Saudi Arabia’s national oil company, which went public last month and currently has a market cap of about $1.8 trillion.

Amazon.com Inc. flirted with the level last year, but the e-commerce company would have to rise more than 7% for its current valuation of $931.1 billion to return above $1 trillion.

These four companies represent more than 15% of the weight of the S&P 500.

The fifth-largest U.S. stock by market cap, Facebook Inc., currently has a valuation of $632.9 billion. The biggest company outside the tech or internet sector is Berkshire Hathaway Inc. in sixth place, valued around $559 billion.