Few corners of the financial universe have been surrounded by as much marketing froth as ESG, which by some estimates represents more than $40 trillion in assets. According to Morningstar, genuine ESG funds held about $2.7 trillion in managed assets at the end of the fourth quarter.

The unfettered boom in ESG debt has created some accounting concerns that are in urgent need of regulatory attention, according to Europe’s markets watchdog.

When Swedish bank SEB AB announced recently that it wanted to buy into the market for carbon credits, what it got was a pile of duds.

In the region that ushered in the world’s first green bond, banks are now building private databases to help their clients navigate the dark side of ESG.