What is the ruling on selling shares of the aforementioned companies (Ezz Steel, Telecom Egypt, Oriental Weavers, South Valley Cement) at a price lower than their purchase price to offset losses, then repurchasing them when the price drops, knowing that there is no fraud or influence on stock movement in the exchange?

If the shares are permissible (halal (definition)), then there is no harm in owning them and trading in them by buying and selling, as Allah Almighty says: "Allah has permitted trade and has forbidden interest (riba)." For the ownership and trading of shares to be permissible, two conditions must be met: that the company's activity is permissible, and that it does not deposit a portion of the shareholders' money in usurious banks to earn interest. However, if the shares are impermissible (haram (definition)), either entirely or in part, then it is not permissible to own those that are forbidden. One can refer to Sharia (definition) boards to identify permissible companies.