First of all, as a Halal investor, you need to know the rules to halal investing and have ethical investment standards also known as shariah-compliance investment. Basic known items include staying away from activities that are prohibited in shariah that include alcohol, pork, weapons, etc. Second, the contract that you are investing with. The contract should also be halal. If you are investing through an interest-based contract in a halal sector it does not become a halal investment. The means/contract of the investment needs to be halal as well. Examples of these contracts are Mudaraba and Musharaka. A platform that helps in that area is Ethis crowdfunding. Ethis is a halal investment company that helps individuals invest in Islamic real estate. Ethis do Mudaraba, Musharaka, Istisna, etc. Preference shares are not halal even though they are shares but because they have attributes of fix returns like an interest-bearing loans.