Is Yahoo still a valuable search engine?

10 years ago, there was a constant competition between Google, Yahoo and other search engines, but today Google is the most used. Bing has recently started to improve since Microsoft being involved with it directly and putting it on default on all Windows/Internet navigator, but since then I've heard nothing about Yahoo. It's still a valuable search engine? Is it worth investing in SEO on Yahoo? Thanks!
Yes, is it. It's one of the major search engines and you shouldn't forget it. If you create a website, you should definitely submit your site to Yahoo, it just means more website hits/traffic.
I guess Yahoo is still alive and kicking although I agree that it is just the 3rd in the list after Google and Bing. Speaking of Bing, I wonder how it was able to overtake Yahoo as a search engine. Does being connected to Microsoft has something to do with it? By the way, I have noticed that Chrome is now the number 2 internet browser, second to Firefox. Maybe it is because of the influence of Google? Oh well, it may be a good competition for the search engines. As they say, the more, the merrier, so let's hope that Bing and Yahoo continue with their search for success to be number 1 in the field. And for now, I know that Google is not taking it easy in maintaining the top spot because their research is continuous as per what I had read in one magazine.