Is it haram to work for companies in which investment is not allowed?
Although, we could not find a specific fatwa on the topic, but logically speaking investing and working are two different aspects.
The basic parameter for employment is that the core activity of the company is halal and compliant and it does not indulge in activities contrary to sharia guidelines.
Being an employee one is not the owner of the company and may not have control over most of the decisions. Whereas being a shareholder one is the owner of the company (however small the shareholding) and as such one may be held responsible for the actions of the company (although the small shareholder also may not have control over the decision making).
So if we apply the share screening criteria for employment purpose, it may not be the right approach. Also, we may find the balance sheet for listed companies and find the ratios and analyse, but what about the unlisted companies?
There are several grey areas which need to dealt on case to case basis, like for example the core activity of the company may not be haraam but some peripheral or extra income may be from haraam sources, like in the case of some software companies.
Also, the individual may be working in a department of a company which is not directly involved or responsible for the haraam activity/income.
The best way would be to seek fatwa from a local mufti explaining the details of the individual situation.
The below fatwa may provide a better understanding.
May Allah swt guide us all to earn halaal.