NEW YORK (TheStreet) -- Petco's IPO announcement may be evidence that the private equity exit boom isn't over just yet.

The pet supply retailer filed documentation with the SEC earlier this week revealing plans to return to the public markets for the third time. The announcement comes just eight months after rival PetSmart was taken private by a group of investors led by BC Partners for $8.7 billion.

Petco has been off of the public markets for nearly a decade. It was taken private by TPG Capital and Leonard Green & Partners for about $1.8 billion in 2006. According to the SEC filing, TPG still owns 46.8% of Petco, while Leonard Green & Partners owns 37.5% of the retailer. Other shareholders include Abu Dhabi Investment Authority and FS Equity Partners.

Petco estimates the pet industry to be worth $74 billion and marks numerous of its own financial highlights in the filing, including achieving positive comparable sales growth across 21 consecutive quarters and growing its store base to more than 1,300 stores. Its net income for fiscal 2014 reached $75.3 million on sales of nearly $4 billion.

Private equity exits surged in 2014. Private equity firm Bain Capital called 2014 "the year of the exit" in its 2015 Global Private Equity Report, citing that exits from buyouts reached $456 billion from 1,250 sales last year, surpassing an all-time high by a wide margin.

Bain also noted that holding time has lengthened and predicted that it will continue to stretch "because so many holdings acquired during the boom years have yet to be fully exited." For buyouts exited in 2014, the median holding period was 5.7 years, increased from 3.4 years in 2008.

Sales to strategic buyers continue to be the biggest channel for buyout-backed exits, and corporate acquirers purchased 715 private equity portfolio companies in 2014.

Another 210 exits came in the form of IPOs, up 20% from 2013. Their value increased 48% to $86 billion.

"The IPO market has been a really good outlet to exit the last couple of years, primarily because the market has done very well. There's a lot of exuberance in the marketplace, the broader markets have done well, IPOs have done very well," said Neil Dhar, U.S. Capital Markets Leader at PricewaterhouseCoopers. "That has been a very popular way of coming out of investments in the natural part of the cycle."

Some major private equity IPOs have taken place worldwide in recent years.

Listed below the 10 biggest private equity IPOs to take place since 2006 according to Preqin, a provider of data and intelligence on the alternative assets industry.

Glencore International

Glencore International, a diversified natural resources company headquartered in Baar, Switzerland, raised 6.8 billion British pounds -- more than $10 billion dollars -- in its 2011 IPO. It was the largest capital raised by an international company in London.

In 2009, Glencore International sold $2.2 billion of convertible bonds to investors including BlackRock (BLK - Get Report) , First Reserve Corporation, Zijin Mining Group and the Government of Singapore Investment Corporation, setting the stage for its initial public offering two years later.

China Pacific Life Insurance

China Pacific Insurance, the country's third-largest insurer, raised 30 billion yuan ($4.1 billion) in its Shanghai initial public offering in 2007. At the time, it marked the second-largest mainland share sale by a Chinese insurance company.

A group of investors led by Carlyle Group (CG - Get Report) first bought into the company in 2005, purchasing 25% of its life insurance arm for $410 near the end of the year. In 2007, it increased its investment even more and converted it into a 17% stake in parent company China Pacific Group.

In 2007, the Financial Times estimated Carlyle's total investment to be $800 million for a stake worth $4.7 billion, meaning a nearly six-fold return.

Evonik Industries

German industrial corporation Evonik Industries began trading on the Frankfurt and Luxembourg Stock exchanges in April 2013. Preqin estimates the company raised 3 billion euros (about $3.9 billion).

Evonik's path to going public was a long and winding one, and it shelved IPO plans more than once.

"We have learned a painful lesson on the topic of IPO," said CEO Klaus Engel when speaking to reporters in 2013. "What was difficult was finding a consensus between the owners' valuation and what the market was willing to pay at that point in time. Now we have done it the other way around."

To get it to the public market, Evonik owners RAG Stiftung and CVC Capital Partners sold a 12% stake in the company to investors and followed up with a public offering in April. Private equity firm CVC had initially purchased a 25% stake in the company in 2008.

HCA Holdings

In 2011, HCA Holdings (HCA - Get Report) raised $3.79 billion in the largest U.S. private equity-backed IPO ever. A total of 126.2 million shares were sold, 2.2 million more than expected. The sellers included

The hospital and health care facilities operator was acquired and taken private in 2006 in a leveraged buyout including investors Bain Capital, Citigroup (C - Get Report) , Merrill Lynch Global Private Equity and Ridgemont Equity Partners. The initial bid valued the company at $21 billion, but including the assumption of its debt, its value jumped to $33 billion.

HCA Holdings joined the S&P 500 in January 2015, replacing Safeway. Its current market cap is around $37 billion.

Bank of Communications

Bank of Communications, one of the largest banks in China, was listed on the Shanghai Stock Exchange in May 2007. It raised 25.2 billion yuan (about $3.3 billion) in its second public listing. The company raised $1.9 billion two years earlier in 2005 in its Hong Kong Stock Exchange IPO.

Chinese private equity firms Junsan Capital and Co-Power Venture Capital had invested in Bank of Communications in 2006.

Charter Communications

In May, U.S. telecommunications company Charter Communications (CHTR - Get Report) announced plans to merge with Time Warner Cable (TWC) in a deal valued at $78.7 billion. It's hard to believe that less than six years prior, Charter was issuing a public offering of its stock as part of a bankruptcy restructuring.

Charter filed for Chapter 11 bankruptcy in March 2009. The filing restructured $8 billion of the company's debt and cancelled all existing shares of its common stock.

It emerged from bankruptcy later that year and subsequently returned to the public markets in September 2010, raising $3.2 billion. Sellers included Apollo Global Management (APO - Get Report) , Crestview Partners and Oaktree Capital Management, which took control of the company in 2010.

Apollo, Crestview and Oaktree remained in the mix in subsequent years and in 2013 sold a 27.3% stake in Charter to Liberty Media (LMCA) for approximately $2.6 billion.

Aozora Bank

In November 2006, Aozora Bank raised 351 billion yen (about $3.0 billion) in an initial public offering in Japan.

Cerberus Partners was among the shareholders selling in the IPO. The U.S. buyout fund gained control of Aozora in 2003 when it bought a stake held by Softbank Corp. Prior to the IPO, it owns 62% of the Japanese bank.

Cerberus ended its control of Aozora in 2013 when it announced plans to sell as many as 632.5 million of its shares in the company valued at $1.8 billion.

Kinder Morgan

Energy infrastructure and pipeline company Kinder Morgan (KMI - Get Report) raised $2.9 billion in its 2011 IPO. It ended its first day of trading at $31.05, up from its initial price of $30.

Kinder Morgan's private equity owners, including AIG (AIG - Get Report) , CalPERs, Carlyle Group, Goldman Sachs Merchant Banking Division and Riverstone Holdings, sold shares in the offering, while the firm's management did not.

Company founder Richard Kinder spearheaded a management-led buyout to take Kinder Morgan private in 2006. "Clearly a lot of money has moved into private-equity funds," he said in an interview with The Wall Street Journal at the time. "It makes a transaction like this much more doable than before."

The deal to take Kinder Morgan private closed in 2007 for $22.4 billion.

Tognum Group

Tognum Group, now renamed as Rolls-Royce Power Systems, went public in 2007 on the Frankfurt Stock Exchange, raising more than 2 billion euros (approximately $2.7 billion) in the process.

Private equity firm EQT bought Tognum from Daimler Chrysler in 2006, creating it out of the company's off-highway MTU Group. EQT unloaded part of its Tognum shares in the 2007 IPO, and in 2008, it sold its remaining 22.3% stake in the diesel engine manufacturer back to Daimler.

Ally Financial

Ally Financial (ALLY - Get Report) , the auto and mortgage lender rescued by the U.S. government in the 2008 financial crisis, returned to the public markets once again in 2014. The company raised $2.4 billion in its initial public offering on the New York Stock Exchange.

The company originally filed to go public in March 2011 but repeatedly delayed its plans. The stock stumbled out of the gate and dropped in its trading debut, but then-CEO Michael Carpenter wasn't worried.

"I personally don't care one way or another how the stock trades, a few pennies one way or another today," he said in a phone interview with Bloomberg.

Aozora Bank, Cerberus Capital Management and Citigroup bought 51% of Ally, then called General Motors Acceptance Corp., for $14 billion in 2006. Two years later in 2008, the United States Department of Treasury invested $5 billion in the company through the Troubled Asset Relief Program.


This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.