Does he have the right to make an agreement with someone who is working in the company that he will tell him when prices are going to rise?

Firstly:

Undoubtedly every company has its secrets, programs, plans and way of dealing with its customers in a way that will guarantee that it will succeed and continue to operate.

It is dishonest for a worker to tell a customer about the company’s secrets and future plans; rather that comes under the heading of betrayal.

If the agreement is with an employee of the company, that he will tell him of price rises and the new price in return for some compensation, material or otherwise, this is not permissible because of what it leads to of betrayal and consuming people’s wealth unlawfully.

Secondly:

If we assume that the purchaser has acquired this information, he may benefit from it by buying as much as he wants.

We asked our shaykh, ‘Abd ar-Rahmaan al-Barraak (may Allah preserve him) about this issue, and he said:

There is nothing wrong with benefitting from this information when buying from this company, because he is going to purchase at that day’s price, and that will not harm the company.

But the employee who has been entrusted with information has no right to disclose what he has been entrusted with.

And Allah knows best.