Some of the largest LBOs agreed during the heady days of 2006 and 2007 are readying record-setting IPOs.

Outside observers of the leveraged buyout industry – and even some insiders – may have assumed that all of the large, high-profile deals done in the credit-fuelled period of 2006 to 2008 were doomed.

So private equity professionals were understandably cheered when Kinder Morgan filed its plans for a $2.3 billion share sale that could become the largest-ever private equity-backed initial public offering in the US.

Goldman Sachs, Highstar Capital, The Carlyle Group and Riverstone Holdings led the pipeline operator’s $27.5 billion buyout in May 2006, at the time the second-largest buyout on record. It would soon be eclipsed by the $32.7 billion buyout of hospital operator HCA (led by Bain Capital and Kohlberg Kravis Roberts); the $38.9 billion Equity Office deal (The Blackstone Group); and the $43.8 billion buyout of utility company TXU (KKR, Goldman).

Kinder Morgan’s prospectus noted its private equity sponsors would sell 80 million shares at a maximum price of $29 per share, which implies a deal value of $2.3 billion and reportedly may result in nearly a 3x return multiple for some of its backers.

If the offering prices at that level, it will exceed the $1.9 billion offering in January of TV ratings and research company Nielsen Holdings. That IPO priced at $23 and quickly jumped to more than $25 per share, providing a boost to the consortium that in 2006 took Nielsen private in a $10 billion LBO and allowing it to pay down debt. Nielsen’s sponsors included KKR, Thomas H Lee Partners, Carlyle and Blackstone.

“There’s been a slight improvement in PE-backed IPOs,” says Scott Sweet, senior managing partner at Florida-based IPO advisory firm IPO Boutique. “Nielsen was priced well, performed well and also was high profile. And there are others in the pipeline, like Toys R Us and HCA,” Sweet added, pointing to two KKR- and Bain-backed companies that last year filed for IPOs.

HCA, which has already paid a reported $4 billion in dividends to its sponsors, filed plans for a $4.6 billion IPO that is expected to price in March and help reduce the company’s debt burden.

Its progress and many others will be watched closely for validation the mega-boom wasn’t a bust: at least 21 private equity-backed IPOs worth a combined $9.7 billion are in the pipeline, according to data provider Dealogic.