(Bloomberg) — Aggressive spending on artificial intelligence is mostly being rewarded in the stock market these days. But when it comes to Amazon.com Inc., not so much.Most Read from BloombergWhy the Federal Reserve’s Building Renovation Costs $2.5 BillionMilan Corruption Probe Casts Shadow Over Property BoomHow San Jose’s Mayor Is Working to Build an AI CapitalAmazon’s shares have gained about 3% this year despite the company’s heavy outlays on AI, which it is touting as a path to greater effi