The private equity industry is on a spending spree like never before. Buyout barons Blackstone Group Inc., Apollo Global Management Inc., KKR & Co. and others account for a record 30% of global transactions this year, with deal flow and fundraising close to all-time highs.

Investors are flush with cash and looking to put the money to work. In the U.S., a private equity consortium recently announced one of the biggest leveraged buyouts of all time. And in the U.K., PE funds have been at their busiest since the financial crisis, targeting household names including grocery chain Wm Morrison Supermarkets Plc. By mid-2021, the sector had amassed a record $3.3 trillion of unspent capital, including $1 trillion held by buyout funds, giving it significant fire power for fresh acquisitions.

“Lots of funding and investment opportunities have created a real boom in private equity,” said Meziane Lasfer, a professor of finance and researcher on private equity at Bayes Business School in London. “The more PE firms take over companies, the more they grow, the more cash they can extract from their investments, the more opportunities they can take.”

The industry’s success, however, is drawing greater scrutiny from authorities across the globe, potentially limiting future returns.

The industry has nearly tripled in size since the start of 2011. Combining equity deal value, exit value, and fundraising, the sector is on track to top $1 trillion by year-end, Hugh MacArthur, Head of Global Private Equity at Bain & Co, wrote in July.

While critics say managers simply extract as much cash as possible from highly leveraged and vulnerable companies, fans like to highlight the sector’s track record of growing businesses while outperforming equities. The industry’s performance is hard to measure. Academic research on this point is mixed and there’s no agreement among investors on a standard metric.

The money flows show little sign of slowing down. Private equity is now starting to expand into the retail market by rolling out products for household investors in the hope of tapping a savings pool worth upwards of $74 trillion.

The biggest buyout names have moved into credit, real estate, infrastructure and other areas, leading to new records in fund raising.

New York-based KKR alone raised a record $59 billion in the second quarter across its various private market strategies. Carlyle Group Inc. is seeking to raise as much as $27 billion for its latest flagship fund, in what would be the largest-ever private equity pool.

The latest asset class that everyone wants is secondaries: vehicles that focus on buying existing portfolios of private equity holdings from investors who want to exit before funds mature.

Secondaries also step in to buy out existing investors when fund managers want to continue holding an asset beyond the life time of the fund. The latest deal: In mid-September CVC Capital Partners agreed to acquire $8 billion secondary buyout specialist Glendower Capital.

The industry’s drive into different investment strategies has helped push overall assets under management at major managers to levels exceeding many leading mutual fund houses.

With bigger funds come bigger deals. Private equity is steadily creeping into transactions that were previously the preserve of big businesses or sovereign wealth funds.

By clubbing together, several PE funds and key investors can pool resources to take on ever more ambitious targets. That’s what happened in June when Blackstone, Carlyle, and Hellman & Friedman, alongside Singapore’s GIC Pte in June announced a majority stake in Medline Industries Inc. in a deal worth more than $30 billion.

Also aiding the rise of ever larger deals has been the proliferation of private credit funds that have stepped in post-financial crisis to replace banks in some of the more riskier lending areas.

The U.K. has been a center of deal activity. Thanks to a permissive takeover code, a hands-off approach from government, and cheap valuations, the U.K. is on track for its busiest year of private equity deals since the financial crisis.

At present Clayton Dubilier & Rice LLC, Fortress Investment Group and others are trying to buy blue chip stalwart Morrison. Meanwhile, U.K. authorities are probing another PE deal, a bid by Advent International Corp-owned Cobham Ltd. to buy rival Ultra Electronics Holdings Plc, on national security grounds.

To be sure, while there is little at the moment to stop the flood of money into private equity, the sector’s growth is drawing more attention from regulators and politicians.

In the U.S, senior Democratic Party members are debating measures that would make it harder to add leverage on deals, as well as end tax breaks for fund managers. While in the U.K., a mid-market tabloid’s on-going campaign against private equity deals shows how the once obscure industry is starting to attract more hostile media.

More significantly, China has announced a crackdown on private equity funds raising money directly from domestic retail investors. That effort may put a significant dent in global fundraising numbers.