steve jobs eric schmidtAP/Paul SakumaApple founder and then-CEO Steve Jobs, left, and Google's then-CEO (now Chairman) Eric Schmidt, right, smile as they introduce the iPhone in 2007.
Alphabet, Google's parent company, has overtaken Apple to become the most valuable company in the world.
Alphabet closed Monday at $518 billion, but in after-hours trading on Monday, Alphabet spiked over 5% at one point following a strong earnings report, making Google worth roughly $544 billion. At that point, Apple's market capitalization stood at $534 billion.
As a whole, Alphabet posted total revenue of $21.32 billion in the fourth quarter.
Alphabet beat on both the top and the bottom line, posting earnings per share of $8.67, which beat analyst expectations of $8.09. 
Alphabet's primary revenue-generating engine is Google, of course. During Monday's earnings call, Google CEO Sundar Pichai noted that seven Google consumer products have more than 1 billion monthly active users, including Gmail, Search, Android, Maps, Chrome, Youtube, and Google Play.
But as quickly as Google can make money, parent company Alphabet can spend it. "Other Bets" revenue, which includes Google's long-shot projects like self-driving cars and internet balloons, posted an operating loss of $3.56 billion with only $448 million in revenue. 
Wall Street liked Alphabet's earnings, spiking the stock over 8% in after-hours trading before settling down closer to 5%. 
Of course, we'll see if Alphabet will officially claim the lead tomorrow morning, when the market opens.