For months now, Amazon.com Inc. NASDAQ: AMZN has been one of the strongest performers among the mega-cap tech names. Shares are up roughly 40% since April, a rally driven by consistently strong earnings reports and near-unanimous support from Wall Street analysts. With equities broadly in risk-on mode and major indices hitting all-time highs, Amazon has thrived in the kind of environment where it historically performs best. That backdrop makes the downgrade from Zacks Research towards the end of August all ...