Tesla Inc. has lost top executives at a faster clip than similar companies have, with turnover “dramatically higher” at the Silicon Valley car maker’s top echelons, an analysis by Bernstein has found.

Tesla TSLA, +5.04% in July announced the departure of its No. 2, Chief Technology Officer J.B. Straubel, its highest-profile executive departure yet. Employee churn at the company, however, has long been under scrutiny on Wall Street and beyond.

Analyst Toni Sacconaghi said in a note Wednesday he set out to address the issue “in a fact-based way,” comparing Tesla with similarly young, fast-growing, and mostly Silicon Valley-based companies such as Snap Inc. SNAP, +1.52% , Uber Technologies Inc. UBER, +3.32% , Lyft Inc. LYFT, +2.83% , and privately held Airbnb Inc.

Read more:Tesla’s key executive departures, in one handy list

“Our analysis indicates that Tesla’s annualized executive turnover level has been 27%, notably higher than the cohort average of 15%,” but not “outlandish,” Sacconaghi said, with Snap, with 24% turnover, and Lyft, with 23%, experiencing turnover nearly as high.

Tesla’s turnover of executives reporting directly to Chief Executive Elon Musk, however, has been, at 44%, “dramatically higher than the turnover of CEO’s direct reports at comparable companies,” which has averaged 9%, Sacconaghi said.

“While one could argue that (Tesla’s) high turnover reflects its unique and demanding culture, we worry that such turnover not only causes instability ... but could also reflect more significant concerns among senior leaders about the company’s direction or workplace practices,” Sacconaghi said.

Related:Tesla’s margins are ‘more solid than they appear,’ this analyst says

Tesla did not immediately return a request for comment. The stock on Wednesday was poised to end at its lowest since July 2 amid broader market weakness.

Musk also has more people reporting to him, or about 17 to 18 executives, than it is more typical in other companies (eight to 12 employees), “which is particularly notable given Musk’s other commitments, including (Space Explorations Technologies Corp.),” Sacconaghi said.

“Worrisome” observations include the finding that Tesla has experienced “unusually high” turnover in key positions: chief accounting officer, general counsel, head of global security, and vice president of Autopilot, with three or more people taking over these roles in recent years.

See also: Tesla gets rid of cheaper Model S, Model X options

And in several cases high-profile executives hired externally departed in “short order,” including many who left in under a year, he said.

In the case of Straubel, the former CTO said he would be taking on an “advisory role,” with vice president of technology Drew Baglino slated to take over Straubel’s duties.