This sentence's very hard to understand for me as well. It might has been written grammatically incorrect. Someone had a plan for overhauling Dow Jones. Asking $5 bilion to overhaul (wound up)Dow Jones was to much for investors.
This sentence is difficult to understand and seems to be missing some elements around the underlined phrase above. Here are some sentences that use variations of that phrase to illustrate how it could be used properly.
The $5 billion to fix the problem wound up being too much to ask of investors.
The amount of money requested from investors was too much to ask of them.
Requiring that much homework wound up being too much to ask of the students.