Amazon.com Inc. reported fourth-quarter earnings that surpassed Wall Street's expectations, with revenue reaching $187.8 billion, up 10% from the previous year, and net income soaring to $20 billion. Despite the strong performance, Amazon's shares fell more than 3% in after-hours trading due to a disappointing sales forecast for the first quarter. The company projected operating income for the current quarter to be between $14 billion and $18 billion, which is below the $18.2 billion that analysts had anticipated. First-quarter sales are expected to reach up to $155.5 billion, falling short of the $158.6 billion forecast by analysts. This shortfall is attributed to an 'unusually large, unfavorable impact' from foreign exchange rates. Amazon's increased spending on artificial intelligence (AI) infrastructure, particularly for its cloud computing arm, Amazon Web Services (AWS), which reported revenue of $28.79 billion and a growth rate of 19%, has raised concerns among investors about the company's future profitability and the return on its AI investments. The company highlighted the success of its holiday shopping season, which contributed significantly to its quarterly performance.