He works in marketing of a program to deal in shares
Question

                I am a young man working in a company that markets programs for dealing in shares on the internet. It enables the user to see the prices of shares and all the increases and decreases in prices, and to make a decision based on that. The program offers all shares of companies and banks, regardless of whether they are riba-based or not. Based on that, I would like to know whether my work in this company is halaal or haraam?.
Praise be to Allah.
    The basic principle with regard to such products that may be 
    used for both halaal or haraam purposes is that reference should be make to 
    knowledge and certainty about the purchaser or user. 

    If it is certain that they are going to be used for haraam 
    purposes, then it is not permissible to produce them or sell them. 

    If it is certain that they are going to be used for 
    permissible purposes, then there is no dispute that it is permissible to 
    produce them and sell them. 

    If both are possible, and we do not know whether people will 
    use them for halaal or haraam purposes, then we should act on the basis of 
    what we think is most likely. If the producer or seller thinks it most 
    likely that the buyer will use it for haraam purposes, then it is haraam to 
    sell it to him. If he thinks it most likely that he will use it for halaal 
    purposes then it is halaal to sell it to him. 

    Unfortunately if we study the stock market in the Arab and 
    Muslim world – let alone the West – we will see that most of the shares that 
    are bought and sold in those markets are shares in haraam companies such as 
    banks, insurance companies and companies that make haraam products, and 
    those that buy and sell permissible products take riba-based loans and 
    invest their wealth in riba-based banks. These are what some contemporary 
    scholars call “mixed companies” and companies whose shares are haraam 
    according to the correct opinion. 

    Hence it is not permissible for anyone to help these stock 
    markets with their work, because of the definitively haraam things that it 
    involves, or because of the haraam that is mixed with halaal, and the halaal 
    is very small in comparison with the haraam. Based on this, we do not think 
    that you should work in marketing these programs, because it is cooperating 
    in sin and transgression, and Allaah says (interpretation of the meaning):  

    “do not help one another in sin and transgression. And 
    fear Allaah. Verily, Allaah is Severe in punishment”

    [al-Maa’idah 5:2]

    Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) 
    said: 

    Every garment that it is thought most likely will be used for 
    sinful purposes, it is not permissible to sell or tailor it for one who is 
    going to use it for sinful and wrong purposes. End quote. 

    Sharh al-‘Umdah (4/386). 

    In the answer to question no.
    11517 we quoted the response 
    of Shaykh Ibn al-‘Uthaymeen (may Allaah have mercy on him) (to a question) 
    about the ruling on operating a computer program for a company that would 
    use it for both halaal and haraam purposes. The Shaykh replied: 

    If most of the work which this company does is haraam, then 
    it is not permissible for him to do that. If most of what they do is 
    permitted, then it is permissible for him to do it. If they (haraam and 
    halaal elements) are the same, then he should not do it, on the assumption 
    that what is haraam will outweigh what is halaal. And Allaah knows best. 

    For more information, please see the answer to question no.
    75007. 

    And Allaah knows best.