Advent's GPE VII LP is the largest buyout fund to be raised since the collapse of Lehman Brothers Holdings Inc. in September 2008 and the beginning of the global financial crisis, according to data from industry intelligence firm Preqin.

The fund originally was targeting €7 billion and a hard cap of €8 billion, but raised the latter to €8.5 billion after receiving strong support from limited partners, Advent said.

"We are very pleased with the reception from investors," Advent managing partner David Mussafer said. "We felt that the fact that we have an old-fashioned partnership here at Advent and are only focused on a single line of business resonated with some of our investors.

The fact that we've been in business for 28 years is something investors seem to respond positively to," Mussafer added.

In October, Blackstone Group LP had a final closing of its Blackstone Real Estate Partners VII fund with $13.3 billion. While larger than Advent's new fund, it is not strictly a buyout fund because it is devoted solely to real estate investments.

Fundraising for Advent's new fund was not only successful, it was also relatively quick. Advent said the fund officially launched in March, meaning it was raised in about eight months, compared to the average 16.8 months it has taken private equity firms to close funds during 2012, according to Preqin estimates.

In fact, in June, only three months after it was launched, the Advent fund held a first close of €5.8 billion, according to information from the Canada Pension Plan Investment Board, which said it had committed $600 million to the fund as of that date.

Advent's new fund will invest primarily in the developed markets of North America and Western Europe and selectively in other global markets.

"The fact that we continue to have volatility in [developed markets in North America and Europe] in some ways is creating opportunity," Mussafer said. "We've actually seen some mini cycles, particularly on the credit side, where the markets have opened and closed and created opportunities for transactions that might otherwise have been more difficult."

A small part of the new fund could be invested in Asian markets, according to Bob Brown, Advent managing director and global head of limited partner services in the U.S. "Over the last three or four years we have been looking at developing a presence in Asia, India and China specifically, and while we don't anticipate putting a significant portion of the new fund in these markets they are important markets."

Just like previous Advent funds, GPE VII LP will invest in technology, media and telecommunications, retail and commerce, industrials, healthcare and business services.

Advent has closed one investment through the new fund. In August it acquired a majority interest in AOT Bedding Super Holdings, which owns the Serta brand, and Simmons Bedding Co. for about $3 billion. Serta and Simmons are two of the largest mattress manufacturers in the world.

Advent has also agreed to invest in two other businesses. In October it agreed to buy KMD A/S, one of Denmark's leading IT services and software companies for an undisclosed sum. The same month it also agreed to acquire Cytec Industries Inc.'s coating resins business for $1.15 billion.

It remains to be seen if Advent's new fund will end the year as the largest buyout fund since the Great Recession. Warburg Pincus LLC is still seeking commitments for its Warburg Pincus Private Equity XI fund which, at a target of $12 billion, could beat Advent's latest fund in terms of size. Warburg Pincus had raised a total of $5 billion for this fund as of May, Preqin data shows.

Since its inception in 1984, Advent has raised about $37 billion and completed 279 transactions in 35 countries, according to firm information.