This article originally appeared on CFO.com.

Is it time to split up?

Each week brings with it news of the latest multi-business public company looking to ignite shareholder returns by separating. Sometimes compelled by external pressure from activist investment funds, spin-offs are taking place across a range of industries. HP Inc. and Hewlett-Packard Enterprise, eBay and PayPal are among the most recent examples, and the list keeps growing.

Corporate breakups may be in vogue, but are they worth it? Separations are costly; one-time costs typically amount to 1% to 2% of revenue, and sometimes more for the most complex separations. They’re time-consuming, too, generally taking 12 to 18 months from decision to close. As anyone who has embarked on a separation can attest, they’re also resource intensive and distracting for an organization, causing a high degree of inward focus.

The big question for boards and CEOs pondering such a move is, “Does the breakup succeed in creating shareholder value?” The answer is, “sometimes.” We determined this by analyzing the performance 18 months post-separation of 40 transactions involving companies valued at more than $1 billion in the 2001 to 2010 time frame. We focused on deals in which two separate public companies were formed out of a portfolio in which there had been some level of strategic and operational integration.

Based on our analysis, the top third of separations delivered significant value: The combined market cap of the new businesses after separation exceeded their pre-spin value by more than 50%. That’s the good news. But in another one-third of the cases, the combined market cap of the new companies was 40% less than their pre-spin value 18 months after separating.

This tells us that separations are “high beta” events, requiring CEOs and boards to thoroughly understand the most important contributors to success and to take a measured approach to spin-offs, even in the face of external pressures from investors.

Read the full article at CFO.com.