Morten Kiil: "Do you know what money I have bought these shares with? […] It is the money that Katherine and Petra and the boys will have when I am gone. […] the whole of the money is invested in the Baths now. (5.171-173)
Kiil is trying to use money as a weapon against his son-in-law. Of everyone who tries to tempt the Doctor to betray his principles, Kiil gets the closest. Here the money is directly tied to the well being of Dr. Stockmann's family. Ultimately, Kiil's attempt to gain power over the Doctor fails, but the fact that Dr. Stockmann briefly considers backing down seems to show just how strong a force wealth can be.