Is it ethical to develop software for financial company?

First of all Sadhu for the skillful mental action and state of conscious and moral shame.

The Buddha, so his disciples, did not taught laypeople much in regard of "best" livelihood, Justme. He focused on the livelihood he chose as most proper and praised like all wise the going forth, as the best means of livelihood.

It's properly good, in regard of right view, to "start" with right livelihood for the mind, which is best feeded with right thoughts, intentions and right view.

There is at least no food (for pleasure), no livelihood, no entertaining (upadana) that does not require sacrifies and pain at least, if follow the lines in the circle of trade and exchange. So one seeks for the most harmless food to use it for overcoming food. Here with right livelihood.

What ever extend one sees such and understands to ste ossible out of that, go for better livelihood, maybe even to the highest right livelihood as "begging" recluse, what ever makes the conscious ligher and one self out of feeling remorse, is good, if not simply hypocritical.

There are three ways of actions: bodily, by one self; by speech (all kind of expressions), in ordering or encouraging others; and by mind (in toughts by wishing, agree, acepting, aprove). All three action, if based on mind outwardly as well, have dependent on the quality (skillful, unskillful, neutral) their "equal" results.

So most actions, then followed by one adopting in livelihood, can only right considered in ones own sphere and situation. While answering your question general with a categorical yes or now would be wrong and just a view.

Best is always to follow ones conscious, where ever it (good considered) might be more lighter and dependent on current possibilities of change, step by step.

While one could formal argue "but if doing and not agree with certain outcomes" might be sometimes a possible way, especially if not having ways to chance livelihood and being "somehow a slave", going after a live on two vehicles will lead to painful accidents.

There are cases where worker "ungrateful" opposte their leaders/chiefs, the feeding hand: such is very unskillful. But to encourage ones chief or leader, while still bound, to walk better, more virtuose ways, nd act with right intention in all spheres possible for one, could help in a dependig situation. A soldier might be able to seek after work in the kitchen or as ambulance, to give a figural sample.

Even if there are no "this, and nothing else is right" grasps are given here, it might contain food for own good investigation for the situation and for sure the best teaching, for all situation, very clear, is given by the Buddha to his son. It's good to follow just this mode, where ever one for now may walk or stand: Instructions to Rahula at Mango Stone

[Note: This is a gift of Dhamma and not meant for commercial purpose or other low wordily gains by means of trade and exchange.]

As a trading platform for financial markets, it is something ethically neutral.

Working in the field of business software automation, I have a similar quandary since I am essentially helping businesses with questionable purposes and also making things so efficient that people will lose jobs.

As the other answers would suggest though, it is one's intention that counts and thinking about the secondary and tertiary effects of one's actions becomes easily unpredictable. Buddha has himself said karma is deep and it is a pointless game to understand all levels. Better to simply follow the Eightfold Path, confirm that you are following the basic tenets of Right Livelihood and keep walking towards goal of the Three Trainings.

I would thus suggest to focus on the immediate positive effect you are creating and what you can immediately see. The meat after all was not ordered specifically for you. Should everyone in the world focus on the immediate positives, things would average out to wholly good in the end through all levels of society.

I assume you're looking for an answer based on this definition:

A lay follower should not engage in five types of business. Which five? Business in weapons, business in human beings, business in meat, business in intoxicants, and business in poison.

I'd guess so (that it is ethical or not inethical to develop software for a financial company).

Consider telecommunications or telephony software, for example: theoretically the internet and telephone system is also used for trading meat, but, that's not exactly your responsibility: the same is true for anything -- making cars, for example: a few cars, too, are used in the trade of meat.

I think I mostly just avoided employment with aerospace (i.e. defence, weapons) manufacturers.