Nvidia briefly reached a market capitalization of $4 trillion on Wednesday, making it the first company in the world to reach the milestone and solidifying its position as one of Wall Street's most-favored stocks.

A combination of tight credit spreads, a low VIX, placid bond markets, and high valuations for riskier assets could be a sign investors are complacent.

Nvidia achieved a $1 trillion market value for the first time in June 2023 and tripled it in about a year, faster than Apple and Microsoft, the only other U.S. firms with a market value of more than $3 trillion. Microsoft is the second biggest U.S. company, with a market capitalization of $3.75 trillion. Its shares were last up 1.3% at $503.