What happened

Shares of MobileIron Inc. (NASDAQ:MOBL) were down 11.2% as of 1:30 p.m. EDT Wednesday, after the mobile-device-management software company announced disappointing preliminary third-quarter results and the unexpected resignation of its CEO.

More specifically on the latter, MobileIron stated that its board has appointed CFO Simon Biddiscombe as its new president, CEO, and a member of the board. According to MobileIron's press release today, the change is effective immediately and "follows the mutual decision between the MobileIron board and CEO Barry Mainz that Mr. Mainz will leave the company."

MobileIron also stated that gross billings for the third quarter should be between $49.5 million and $50.5 million, up between 5% and 7% year over year and well within its latest guidance for billings of between $48 million and $52 million. However, the company expects revenue to arrive at between $42 million and $43 million, up 1% to 4% year over year, and well below guidance for between $44 million and $46 million.

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So what

Recall that MobileIron shares plunged when it first provided that guidance along with its second-quarter report in late July, as investors fretted over the implications of disappointing new order billings. At the time, Mainz reassured investors that the weakness was primarily the result of temporary delays in closing a few large deals.

But that pullback was also enough to catch the attention of activist investor firm Altai Capital Management, which caused shares to pop earlier this month by opening a 7.63% stake in the company. Altai also revealed that it had engaged in discussions with MobileIron about management, capital allocation and structure, and potential strategic alternatives. I can't help but wonder, then, whether Altai's involvement spurred this unexpected executive turnover.

Now what

In any case, with Mainz moving on, MobileIron is framing the situation as a "leadership transition to accelerate growth and profitability."

Biddiscombe elaborated:

I'm honored and excited to lead MobileIron through its next phase of growth. We believe we have the best products in the market and the right team to drive long-term growth and profitability. Over the last year, we've delivered critical innovations that should allow us to deepen our relationship with our customers. I look forward to leveraging our competitive advantage, strengthening our go-to-market execution, and driving improvements throughout our operations.

MobileIron promised more detail on both its third-quarter results and full-year guidance in its formal earnings release on Oct. 31. Investors will need to wait for more color on what drove the company's leadership change and relative underperformance as it kicked off the second half.

Steve Symington has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.