It seems like 'ask' in the financial sense is subtly different from 'request', also. A request is commonly something you make to someone, which doesn't apply t

It seems like 'ask' in the financial sense is subtly different from 'request', also. A request is commonly something you make to someone, which doesn't apply to the case of offering a sale to an open market. An ask is the thing for which you set your 'asking price', so it's almost closer to a challenge than a request - "I'll reward whoever hits price X with a share of stock". And that subtly different meaning seems to carry over to 'ask' as a common noun. You wouldn't say "the Lunar X Prize was a huge request" because it wasn't requested of any specific group, but you might say "the Lunar X Prize was a huge ask", meaning "whoever tried to meet this bar had a very hard task".