How much of your portfolio do you dedicate to one stock, and is there any mathematical reasons that one should/shouldn’t diversify?

this is a complex topic, you can decide with the so called kelly criterium to decide how much allocate\_criterion
KK is clear on that if you read his site/blog.
There are people as Oliver Kell that went full swing trading leader stocks with medium volatility 100 per cent. I do it sometimes, is really risky but I am an adrenaline junky and I do not care to lose my boomer pension. You should not do it, I suggest you to allocate as KK explain at the beginning of his blog for the first setup.
Regarding diversification there are different theories, we are swing traders looking for momentum burst here, and have 10-15 titles on average. Personally I have now Apple Tesla Lucid and TDD only, where TSLA has the great imbalance, I am betting against Powell, if I lose I am happy because I am contrarian like Marc Faber.

/r/qullamaggie Thread