Assalamu Alaikum. What is the ruling on buying and selling shares in installments?

It is permissible to buy and sell shares if the company operates in a permissible field, and there is no other impediment such as Gharar (excessive uncertainty) or Ghish (deception). However, if the company operates in a forbidden field or deals with Riba (usury), then it is not permissible to buy or sell its shares.