Until yesterday a query such as this http://autoc.finance.yahoo.com/autoc?query=a&callback=YAHOO.Finance.SymbolSuggest.ssCallback yielded a long list of fuzzy/broadmatch
When I was building an app that required stock symbol/company lookup, I tried a few options, and none were very good. I took what I built, and made it public: https://www.stocksearchapi.com
UPDATE
I took this offline due to lack of interest