Credit rating agency DBRS Inc. sees risks to the global financial system from the fast-growing shadow banking sector.

In a new report, the Toronto-based rating agency notes that the sector continues to grow quickly, and that it “sees significant risks stemming from [this] continued growth.”

Since 2010, the sector’s assets have risen by 75%, DBRS reports, from $30 trillion (all figures in U.S. dollars) to $52 trillion, currently.

“Fixed income funds, mixed funds, hedge funds and other collective investment vehicles are driving this shadow banking growth,” it says. “Since 2010, this segment has grown by 130% to $36.7 trillion in assets.”

Total non-bank assets have grown by 61% over the same period to about $185 trillion, and now account for almost half (49%) of total global assets held by financial institutions. The share for non-banks is up from 44% in 2010, DBRS says.

Alongside this robust growth, DBRS says that the shadow banks also have some structural weaknesses that pose significant risks to the financial system.

“Weaknesses in these non-bank financial institutions arising in their maturity intermediation, liquidity, leverage and credit transformation could result in runs that would exacerbate financial market stress,” the report says.

In particular, investment funds are vulnerable to runs, it notes. “Many shadow banking institutions are not well structured to cope with a stressed environment in which market liquidity is sharply reduced and fund withdrawals are accelerating,” the report says.

Additionally, these sorts of firms have less capacity than banks to deal with deteriorating credits in a stressed market, DBRS says. And, it notes that their earnings are typically less diversified, limiting their ability to absorb losses.

DBRS says that it “sees significant risks stemming from continued growth in shadow banking globally.”