If I were you, I would start looking from here

http://www.newzoo.com/free/rankings/top-25-companies-by-game-revenues/

Also, you should look at results (revenues and profits) form the past 3 to 5 years, and see who is growing and who is declining. I don't know the level of detail you need, but that should be a good start.

Thanks. To my luck, I don't really need to be super accurate, since my teacher cares more about another part of the project, but I just couldn't find any reliable sources and I really didn't believe it was Konami.

Thanks again

Microsoft makes the most revenue by video game software out of all the console video game makers. However, some Chinese company is number 1 due to league of legends.

Yea, Activision Blizzard no doubt. EA as second.

Nintendo had a higher market cap than any of the "game only" companys in the past, so it could happen. Hard to speak about MS or Sony since they work in different markets.

The one with 50 percent marketshare and growing

They must be on serious drugs. That, or the influx of NX threads broke the world's balance. :P

I don't think the industry has an undisputed leader anymore. From the mid 80's until the mid 90's, it was Nintendo. Even when Sega was gaining marketshare in the US, Nintendo still pretty much defined what the video game industry was at the time. From the late 90's to the mid 2000's, it was Sony. After that, it was no one. The industry had become so fragmented that there wasn't one company or brand that was absolutely needed. The industry needed Nintendo at one time. It needed Sony at one time. Nowadays, nobody needs Nintendo or Sony. In fact, nobody truly needs iOS or Android. There are more choices and all these different platforms can co-exist together because a wider range of people are gaming nowadays. A company can make all their money on mobile platforms without ever having to touch a development kit for a console. Likewise, a company can successfully do all their business on a console without having to release one single mobile game. Then there's the PC. Publishers can be PC exclusive and still remain profitable.

So to be specific, there's no undisputed leader. Arguably, there's a leader in mobile gaming, a leader in console gaming, and a leader in PC gaming and even that can be disputed.

That trillion number are yen

Acti-Blizz
Valve
EA

Between the three of them, they dominate the industry.

You forgot Ubi-