208:4 Just as a mourner may not work, he may not buy and sell merchandise. If he has merchandise that must be sold immediately or he will incur a loss of his investment, he must consult a Torah scholar. If merchandise is arriving by land or sea which is being sold cheaply now and will not be available later, or if he’s at the market when he receives timely news of a relative’s passing, he may buy and sell merchandise through an agent.
208:5 A mourner is allowed to lend money with interest through an agent to a non-Jew who regularly borrows from him. The same is true of selling goods to one’s regular customers, so that they don’t take their business elsewhere.