Alphabet, the parent company of Google, is seeing its shares fall by 13.4% on Wall Street, putting it on track to lose nearly $500 billion in market capitalization in a single trading session. This decline follows the release of third-quarter earnings, which reached $127.6 billion, missing analyst expectations of $128.2 billion. Despite a 25% overall revenue growth, investors are concerned about the cooling performance of Google's search advertising division and the mounting costs associated with artificial intelligence development, raising questions about the return on these massive capital investments.