Responsa for Sanhedrin 143:2
אמרה תורה ימות זכאי ואל ימות חייב שמיתתן של רשעים הנאה להם והנאה לעולם ולצדיקים רע להם ורע לעולם שינה ויין לרשעים הנאה להם והנאה לעולם לצדיקים רע להם ורע לעולם שקט לרשעים רע להם ורע לעולם ולצדיקים הנאה להם והנאה לעולם פיזור לרשעים הנאה להם והנאה לעולם ולצדיקים רע להם ורע לעולם:
Therefore the Torah said, 'Let him die while yet innocent, and let him, not die guilty.' For the death of the wicked benefits themselves and the world; of the righteous, injures themselves and the world. Sleep and wine of the wicked benefit themselves and the world; of the righteous, injure themselves and the world. The tranquillity of the wicked injures themselves and the world; of the righteous, benefits themselves and the world. The scattering of the wicked benefits themselves and the world; of the righteous, injures themselves and the world.
Teshuvot Maharam
A. Lending charity-funds on condition that the lender share in the profits but not in the losses, is forbidden. The Rabbis who said (B. M. 70a) that a person lending money on such a condition is called "wicked" made no distinction between rich and poor. Since a poor person is not permitted to lend his money on condition that he share in the profits but not in the losses, we are not permitted to do so for him.
Note: The following introduction precedes the answer: Please excuse me for the brief response. For the last two weeks I have been confined to bed and have lost the taste for food. I wrote to you a lengthy response regarding the lending of charity-funds, and sent it to you through a messenger named Marvel. I forgot the lengthy argument and discussion. I remember, however, to have agreed with your reasons and arguments, and to have added the following ….
SOURCES: L. 425; P. 476. Cf. Agudah B.M. 73.