The Blackstone Group has agreed to acquire the tech-enabled benefits and HR platform of Aon PLC (NYSE: AON) for upwards of $4.8 billion in cash. The deal includes a $4.3 billion upfront payment, and $500 million in possible earn-outs. Aon had acquired the business ― which serves around 15% of all U.S. workers ― in as part of its $4.9 billion purchase of Hewitt Associates in 2010, but recently decided that it didn't fit within its core focus area.

• Digging deeper: This is really a quintessential leveraged buyout. It's carving out a slowish-growth, cash-flow steady business that doesn't have too many synergistic complications with its parent company. Plus, Blackstone has some experience in the general sector, vis-a-vis its existing investment in Kronos (a company that's more like a thematic cousin than a rival to the acquired biz). Blackstone's win also comes as a bit of surprise, given earlier (and I'm told erroneous) reports that Clayton Dubilier was in pole position to win the auction. Finally, familiarity can breed buyouts, as some of Blackstone's portfolio companies, such as Hilton, were already customers.

• Bottom line: "This company is oriented toward the Fortune 100, and those companies frankly haven't had massive employment growth over the last couple of years. The opportunity is to take what this company has been doing for the Fortune 100 and expand it to the Fortune 1000… This is not a fixer-upper, nor something that's been ignored by Aon. It's just not their primary focus, and we think we can invest more and innovate more to help it expand." ― Peter Wallace, senior managing director at Blackstone Group, speaking to Axios.