I started trading forex before realizing its haram, now that I've realized is it permissible for me to withdraw my money and use it elsewhere given its lesser than the one i deposited at the begining?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

You bear no sin for withdrawing what is left of your money to invest it in lawful investment projects. Whoever gives something up for the Sake of Allah, He will compensate him with something better. Allah, The Almighty, Says (what means): {And whoever fears Allah – He will make for him a way out And will provide for him from where he does not expect.} [Quran 65:2-3]

It was narrated on the authority of Abu Umaamah that the Prophet said: “…no soul would die until it receives its share of provisions in full. So fear Allah and be graceful in seeking provision (seek it in a proper lawful way), and no one of you should be tempted to seek provision by means of committing sin when it is slow in coming to him. Indeed, what is with Allah can only be attained by obeying Him.” [Abu Nu‘aym]

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Allah Knows best.