NEW YORK ( TheStreet) -- In the boom years before the financial crisis and recession, private equity companies set records in the prices they paid to buy up public and private companies, oftentimes with the help of heavy debt financing.

From January 1, 2005 to January 1, 2008, almost 8,000 private equity deals were done for a total value of $1.81 trillion, according to data compiled by Bloomberg. During that time, KKR's ( KKR) buyout of TXU was the largest takeover at a $43.3 billion price tag and The Carlyle Group was the leading dealmaker, with 125 takeovers at nearly $1 billion each. Since then, the total value of deals has fallen to roughly $970 billion, with the average deal size falling below $150 million from over $400 million a deal previously.

In late 2010 and early 2011, a string of companies like HCA Holdings ( HCA), Freescale Semiconductor ( FSL), Dollar General ( DG) and Dunkin Brands ( DNKN) bought in the I.P.O. boom were taken public by private equity owners as stock investors shrugged off recession fears and rebuilt their appetite for new investments after the Great Recession. Not all companies taken private by the deal makers in the pre-bust years were sold to public investors.

According to Dealogic, Global IPO activity has totaled $142.5 billion so far in 2011, down 8% from last year's equivalent total. In the third-quarter $27.6 billion of IPO activity was the worst since the second quarter of 2009.

This slideshow has the 9 biggest takeover deals that are still on private equity company books. We'll be finding out in coming months and years if these investments will make it to public markets, continue to stay privately held or will be sold to a competitor.

TXU Corp. , renamed Energy Future Holdings, was bought for $43.3 billion by KKR and TPG in 2007. The private equity buyers valued the Texas-based utility company at $43.3 billion when counting the debt that came with it and paid $69.25 a share, 15% above the stock at the time the deal was announced. Because Texas's biggest electricity company was being sold to private investors after years as a public utility, buyers at the time said they would likely hold their investment for at least 5 years. KKR and TPG added $24.5 billion in new debt to finance the buyout.

After the recession hit, markets froze and energy prices fell. In 2008, the company had a pretax loss of almost $10.5 billion and paid almost $5 billion in interest on its debt stock of roughly $40 billion. The company has not yet registered an initial public offering filing.

First Data was bought in 2007 for $29 billion by KKR for $34 a share in cash, roughly 25% above its market price before the deal announcement. The Colorado-based company is one of the world's largest payment processors for businesses and financial transactions. To finance the buyout, banks like Citigroup ( C), Credit Suisse ( CS), Deutsche Bank ( DB), HSBC ( HBC), Lehman Brothers , Goldman Sachs Group ( GS), Citigroup ( C) and Merrill Lynch ( BAC) offered KKR $14 billion in loans.

In August 2011, the company reported that revenue for the first 6 months of the year increased 5.5% to $ 5.3 billion and operating profits increased 47% to $318 million year over year. However, the company has posted a net loss of over $300 million this year. Its outstanding bonds carry sub-investment grade ratinge, according to Bloomberg data. The company has not yet registered an initial public offering filing with the Securities and Exchanges Commission.

In 2007, The Blackstone Group ( BX) paid $26.9 billion for Hilton Hotels, paying $47.50 a share for the hotel giant. Blackstone paid a premium of 40% over the stock price at the time and financed the purchase with roughly $20.6 billion in debt. According to the Wall Street Journal, all of the banks that provided financing for the buyout also worked on Blackstone's 2007 initial public offering.

When the deal to buy Hilton was announced Jonathan Gray, a managing director at Blackstone, said in a press release that "It is hard to imagine a better strategic fit for us than Hilton." The buyout firm paid Hilton roughly 30 times earnings for its hotels, which include Hilton brands, Embassy Suites, Homewood Suites and the Waldorf Astoria. In an interview with Reuters in 2011, Hilton Chief Executive Chris Nassetta said that an I.P.O., "is certainly something we will consider at some point," and added that ultimately it's up to Blackstone. Since the deal was done, Blackstone has renegotiated roughly $4 billion in Hilton related debt.

In 2008, just before the financial crisis hit, Apollo Global Management ( APO) and TPG completed their purchase of Harrah's Entertainment for $17.3 billion. In a sin of the markets exuberance, the private equity firms had to pay $90 a share for the world's biggest casino operator to up a bid of $87 a share made by Penn National Gaming ( PENN), a much smaller casino operator, and hedge fund D.E. Shaw.

In June 2010, Paulson & Co, a hedge fund manager that injected cash into Harrah's by buying an equity stake of almost 10% in the casino company to take on $710 million in company debt. In the fall of 2010, private equity owners and Paulson & Co. tried to sell 31.25 million shares of Harrah's to the public in the range of $15 and $17 a share, but they benched the deal citing market conditions. Harrah's operates about 50 casinos, mostly in the United States and Britain. Unlike competitors Las Vegas Sands ( LVS) and Wynn Resorts ( WYNN), Harrah's does not have a casino in Macau.

In 2006 and 2007, Cerberus could not get enough of Chrysler. The New York-based buyout firm first bough GMAC, the finance arm of the automaker, now called Ally Bank, for roughly $7.4 billion. Cerberus then bought an 80% stake in automaker Chrysler from Daimler ( DDAIF) in 2007 for an additional $7.4 billion, after German owners could not turn the struggling automaker around.

In 2009, when Chrysler and General Motors went bankrupt and the "Big Three" U.S. automakers dropped to one, Cerberus shed its Chrysler holding to the U.S. government after the automaker was rescued from a messy bankruptcy. It also lost all but 15% of its stake in GMAC after a credit market freeze required multiple billion dollar plus government injections. Cerberus kept its ownership of Chrysler Financial, which it later sold in 2010 to Toronto-Dominion Bank ( TD) for $6.3 billion, recoupling a significant piece of its original auto investment.

A 'who's who' consortium of private equity investments led by Menlo Park based Silver Lake Partners that included Bain Capital Partners, Blackstone, Goldman Sachs, KKR, and Providence Equity Partners bought SunGard Data Systems for $11.3 billion in 2005. At the time, it was the biggest buyout since KKR bought RJR Nabisco for $25 billion in most-enthralling buyout battle of the 1980's.

Silver Lake and its partners paid $36 a share and took on $500 million in debt for the Wayne, Pa based company that produces business processing software for financial, public sector and education companies. SunGard is ranked 434 Fortune's list of the 500 biggest companies and has annual revenue about of $5 billion. According to its latest filings, SunGard currently has over $8 billion in long term debt rated CCC+. Its loss income from continuing operations was $96 million this year and the company has not yet registered for an initial public offering since being taken private.

In 2005, Bain Capital Partners, KKR and Vornado Realty ( VNO) bought Toys R Us for $7.5 billion. The investors paid $26.75 a share for the second biggest toy retailer in the U.S.

The Company filed for an I.P.O. in May of 2010 to raise $800 million and sought new revolving credit lines, but it now isn't expected to go public until 2012. Roughly 40% of total sales come during the holiday season and a continued spending and employment slump kept an I.P.O. on the shelves. In July, the company reported revenues were down 1.6% to $29.9 billion and same store sales fell 2.2%. Lower rents boosted overall profit margins, however. Number one toy seller Wal Mart ( WMT) has fallen almost 4% year to date, less than overall markets.

In 2007, Midwestern private equity firm Madison Dearborn Partners paid $7.3 billion for Illinois based computer reseller CDW. Continuing to buy up the neighborhood, Madison Dearborn followed up its buyout later that year by paying $5.75 billion for the Chicago-based investment house Nuveen Investments.

Madison Dearborn paid $87.75 in cash per share for the CDW, seller of computers, hardware and office equipment to business customers, a 16% premium over the trading price of shares prior to its announcement. According to company filings, sales have increased over 8% year over year and overall operating income is up 30%. The company has not yet filed for an I.P.O. with the SEC and has $4.2 billion in debt.

Clayton Dubilier & Rice and KKR bought U.S. Foodservices, the American brand of Dutch food retail giant Royal Ahold for $7.1 billion in 2007. At the time, U.S. Foodservice was the second biggest food service company after Sysco ( SYY) and owner of Monarch Foods, a company that provisioned wagons during the westward expansion of the United States in the 1850s.

After the buyout, investment banks financing the acquisition pulled a $1.55 billion debt sale from unresponsive bond markets and also decided to carry $2 billion financing for the sale on their books as a bridge loan. At the time, the failed debt sale and bridge loan signaled to some that credit markets were beginning an implosion, which would put an end to the buyout boom.

-- Written by Antoine Gara in New York.