The amount is very low, and I'm sure there are fees that will eat any "profit".
It's important to understand the it's not the bank that lend you the money to buy your house, at least not directly. You home is financed by bonds, issued by a sort of credit union. Investors then buy those bonds, pensions funds for instance. The Danish housing marked is extremely stable, so it's a safe place to put your money. So some investors will be willing to take a small lose on buying bonds in homes, in return for safety.
It's important to understand the it's not the bank that lend you the money to buy your house, at least not directly. You home is financed by bonds, issued by a sort of credit union. Investors then buy those bonds, pensions funds for instance. The Danish housing marked is extremely stable, so it's a safe place to put your money. So some investors will be willing to take a small lose on buying bonds in homes, in return for safety.