https://www.reuters.com/article/us-tesla-batteryday/tesla-traders-bet-on-musk-battery-pitch-to-spark-rally-idUSKCN26C11R >Fasten your seatbelt, because Tuesday is Tesla's "Battery Day", and some investors expect Chief Executive Elon Musk's pitch on the electric car maker's energy storage advances to re-energize its rally following a recent 21% stock slump.