Question Summary:
Is it permissible to work as a programmer writing software for banks?

Question Detail:

In light of another question asked on Jul-10-2013 (Fatwa#: 26052) in regards to an investment bank (such as JP Morgan, Goldman Sachs and various others), will it also be permissible to work as a programmer writing software that would be used by traders and other non-trader personnels at this bank?
For example, traders would ask software to retrieve price for a security in order to place an order a buy or sell order of certain quantity with this investment bank and trader appearing as the official executors of this transaction.
Basically,this software can be thought of providing an electronic platform where all traders converge and buy and sell securities issued by various parties. 

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
It will be permissible to work as a programmer writing software as described in your query.
Also take note of point 2 of fatwa #26052. 
And Allah Ta’āla Knows Best
Arshad Ali
Student Darul Iftaa
Trinidad
Checked and Approved by,
Mufti Ebrahim Desai.
http://www.daruliftaa.net/
 
(قَوْلُهُ وَجَازَ تَعْمِيرُ كَنِيسَةٍ) قَالَ فِي الْخَانِيَّةِ: وَلَوْ آجَرَ نَفْسَهُ لِيَعْمَلَ فِي الْكَنِيسَةِ وَيُعَمِّرَهَا لَا بَأْسَ بِهِ لِأَنَّهُ لَا مَعْصِيَةَ فِي عَيْنِ الْعَمَلِ (رد المحتار على الدر المختار 6-391)
 
 الفتاوى الهندية 
مُسْلِمٌ آجَرَ نَفْسَهُ مِنْ مَجُوسِيٍّ لِيُوقِدَ لَهُ النَّارَ لَا بَأْسَ بِهِ. كَذَا فِي الْخُلَاصَةِ. (ج 4 ص 450 دار الفكر)
 
Contemporary Fatwaa p159-164
 
 
 
The Goldman Sachs Group, Inc. is an American multinational investment banking firm that engages in global investment banking, securities, investment management, and other financial services primarily with institutional clients.(Wikipedia)
J.P. Morgan is part of JPMorgan Chase  Co. (NYSE: JPM), a global financial services firm. JPMorgan Chase & Co. is an American multinational banking and financial services holding company, and the largest bank in the United States by assets.(Wikipedia)