Carlyle Group, the second-biggest U.S. private-equity firm, will seek a valuation of $7.5 billion to $8 billion in its initial public offering, according to people with knowledge of its plans.

Carlyle plans to sell a stake of about 10 percent in the IPO and will start marketing the deal to investors as early as next week, said the people, who asked not to be identified because the information is private. The Washington-based firm, which has been gauging public interest since last year, is targeting its share sale in early May, said another person.

At $8 billion, Carlyle would fetch less than half the market value of Blackstone Group LP, the world's largest private-equity firm, which has led an industry push into hedge funds and real estate to reduce its reliance on buyouts. Carlyle had initially sought to convince analysts it deserved a valuation comparable to Blackstone's because its steadier earnings would provide investors with a more stable dividend than most peers', people briefed on the matter said last year.