Are the profits obtained from purchasing goods from a factory that belongs to a large corporation lawful, given that the factory does not allocate equal shares to traders, and there is a manager who mediates to increase traders' shares in exchange for a commission?

If merchants are unjustly prevented from accessing goods, it is permissible for them to deal with the official and pay a bribe to obtain their right if they cannot achieve it otherwise. The sin then falls upon the recipient of the bribe, not the giver. The profits from this trade are permissible. As for an employee who seeks to secure shares outside official working hours in exchange for a commission, there is no harm in him taking it.