Until you can your whole question is pointless. Just in case, Facebook is not a corporation. On the other hand, Samsung is such corporation (just the first name which came to my mind), simply and unpretentiously called Samsung Group (and it is from Korea). Unsurprisingly, this group also includes quite a few affiliated businesses or owned companies busy with financial and banking operations. As per Wikipedia, "Samsung Life Insurance currently holds a 7.4% stake in the South Korean banking company DGB Financial Group, making it the largest shareholder". And this is only what can be called public knowedge, something which you can read about in Internet
Initially, you said corporations "start" their own banks
And I provided you a link which proves my point
Then you complained that it was a way too old. I don't know how it disproves my point. I didn't say that all corporations start their own banks but some certainly do. If you come to disagree, you may have to bring forth more substantial arguments and evidence rather than just claiming that it was 25 years ago. But if you are still going to insist (that 25 years is too long ago), you may have to come up with a corporation that was founded within this time frame. Nevertheless, you may really want to read this. Fill free to ask if you have any questions