768. Doing Business on Chol HaMoed

106:1 It is forbidden to buy or sell merchandise on chol hamoed (even through a non-Jewish agent - Bi'ur Halacha 539:1 s.v. bein liknos) unless one has the opportunity to make a large profit, in which case he may then conduct business in private and have more to spend in honor of yom tov than he had originally planned. (He doesn't have to spend all the profit on yom tov, just some of it - Mishnah Brurah 539:16.)

106:2 If one has merchandise that he is afraid will drop in price below what he paid for it if it is not sold immediately, then he may sell it in order to avoid the loss. If there is no concern that he will lose money, just that he won't make a profit, then it is forbidden to sell the merchandise on chol hamoed because protecting a profit is not like avoiding a loss. (Similarly, he may sell the merchandise in order to pay a loan that, if not paid on chol hamoed, will incur a penalty - Bi'ur Halacha 539:4 s.v. yafsid meihakeren.)