Joby Aviation (JOBY, Financials) has seen its shares tumble 27.5% so far this year, as of 1:01 p.m. EDT Friday, after Morgan Stanley took a more cautious stance on the electric air taxi startup.

Citing an increasing number of issues—uncertainty about trade tariffs, continuing supply chain delays, and problems at Boeing (BA, Financials), one of Joby's major partners—the company cut Joby's shares from Overweight to Equal Weight. Include the continuing operational effect of the epidemic; experts claim the near-term view is more cloudy than before.Morgan Stanley said it's now choosing businesses with more consistent performance, implying that in today's nervous market investors might be less ready to ride out the highs and lows of high-growth firms like Joby.With an average daily volume of almost 12 million shares, Joby is still an active name among traders. As of Friday, its market worth was around $4.93 billion.Promising quieter, cleaner substitutes to conventional helicopters, the firm is hurrying to introduce electric vertical takeoff and landing planes to metropolitan skies. But realizing that goal calls on negotiating a difficult legal environment, increasing manufacturing, and demonstrating actual need. Investors seem, for the time being, to be adopting a wait-and-see attitude.