What do I trade. 50 things - that’s it. Why?  Because in trading, there is a balance between money and time. Both have a correlation. Sacrifice one and it will cost you the other. It’s hard to have a lot of both. 

A basket of 50 (ish) things allows me to:

Become familiar at an intimate level with 50 securities out of thousands. That familiarity brings advantages because the behavior of those 50 things is often quite stable and somewhat predictable. 

Saves time because I only have to back-test 50 things. Backtesting is time consuming and resource intensive. 

Gives me a “sweet spot” of actionable signals that I can act/trade on - I get enough that I’m entering from 2-10 trades per week, but I’m not churning over my account balance at a huge rate. 

Allows me to have “hedge” correlation in my account. If I’m long the tech sector I can also be short oil at the same time - if there’s a rapid/flash crash I can be protected. 

That’s the 50. Enjoy!