The Washington PE giant said Monday that it expects to sell 30.5 million common units priced at $23 to $25 each, raising $701.5 million to $762.5 million before offering costs.

An IPO priced at the midpoint of that range would endow Carlyle with a market valuation of $7.3 billion. That's 8.8 times 2011 economic net income, a profit metric used by most publicly traded PE houses. In addition to cash income, ENI includes future performance fees the firm stands to collect on unsold investments, based on estimates of current value.

The projected ENI multiple is well below the multiples of 11.6 and 13 at which Blackstone Group LP and Kohlberg Kravis & Roberts & Co. LP, respectively, trade. The industry's biggest player, Blackstone, sports a market capitalization of $16.1 billion, with KKR at $9.8 billion.

Another rival, Apollo Global Management LLC, which posted a $300.5 million ENI loss last year, has a value of $5.5 billion.

A Carlyle spokesman declined to comment on Carlyle's value target. But the firm's earnings profile may offer a clue.

For instance, Carlyle lacks the breadth of diversity of Blackstone, a quality that public-market investors prize in PE firms because it can blunt the impact of economic slumps. Only 17.4% of Blackstone's ENI last year was tied to corporate buyouts, with the rest coming from real estate investing, hedge funds, credit funds and M&A advisory fees.

In recent months, as it has geared up to go public, Carlyle has striven to expand its portfolio, most notably with the purchase last July of a 60% stake in fund-of-funds manager AlpInvest Partners NV. The deal boosted Carlyle's managed assets to around $150 billion, second only to Blackstone.

But as Carlyle's IPO filing shows, the firm remains deeply reliant on buyouts. Fully 62% of Carlyle's ENI derived from traditional PE. AlpInvest accounted for $13.6 million of ENI for the six months Carlyle owned it.

Nor is the IPO's timing propitious.

Just last week, distressed-investor Oaktree Capital Group LLC priced its IPO at $43, at the bottom of the range; its shares since have skidded 5%. And the private equity industry as a whole took a beating in last year's market swoon. Carlyle's earnings fell 18% year to year.

Nonetheless, the IPO would make billionaires of Carlyle founders David M. Rubenstein (pictured), William E. Conway Jr. and Daniel A. D'Aniello. An offering priced at $24 a unit would value their stakes at $1.13 billion each.

Neither they nor any of Carlyle's existing shareholders would sell stock in the IPO. The founders' combined economic interest would fall to between 45.6% and 46.2% from the current 51.6%. The three would retain voting control.

Carlyle said it would use the bulk of its IPO proceeds to retire debt. Most of the debt was raised in December 2010 to finance a $400 million dividend to Carlyle's 100-plus partners.

J.P. Morgan Securities LLC, Citigroup Global Markets and Credit Suisse Securities (USA) LLC lead a 21-member underwriting syndicate. The banks would have a greenshoe option to purchase up to an additional 4.58 million shares to cover overallotments.

Simpson Thacher & Bartlett LLP attorney Joshua Ford Bonnie is advising Carlyle. Skadden, Arps, Slate, Meagher & Flom LLP's Phyllis G. Korff and David J. Goldschmidt are counsel to the underwriters.