Amazon reports Q4 ad revenue up 23% YoY to $21.32B, slightly above expectations, and subscription services revenue up 14% to $13.12B (Todd Spangler/Variety)

Todd Spangler / Variety: Amazon reports Q4 ad revenue up 23% YoY to $21.32B, slightly above expectations, and subscription services revenue up 14% to $13.12B   —  Advertising revenue jumps 23% to $21.32 billion … But the company's shares fell in after-hours trading Thursday after Amazon said it expected …