Shares of Shake Shack (SHAK) tumbled sharply to finish Tuesday's regular trading session in negative territory after the company was downgraded by analysts at Morgan Stanley, making it TheStreet's Move of the Day. TheStreet's Jim Cramer, portfolio manager of the Action Alerts PLUS Charitable Trust Portfolio said he’s been saying Shake Shack is too high all along. He warned investors of a big initial public offering lock-up expiration at the end of the month that will drive the stock lower. Analysts at Morgan Stanley lowered their rating on the burger joint to UNDERWEIGHT from EQUAL WEIGHT. The firm still maintained its $38 price target on Shake Shack shares. Morgan Stanley analysts believe that the stock is expensive. TheStreet's Kurumi Fukushima reports in New York.