Is it permissible to dispose of a sum remaining from stolen money after the stock market crash, knowing that reporting the colleague would lead to job loss?

The answer clarifies that you are not responsible for the money you received from your friend before you knew it was usurped, because you were deceived.

After becoming aware of the truth, you must stop disposing of the money and immediately return what remains of it to the workplace. What you disposed of after becoming aware of the truth is considered your responsibility.

You can disclaim responsibility before the workplace by stating that your friend deceived you and concealed the matter from you. The money can be returned indirectly, ensuring its return to its rightful owners and avoiding harm to you.