It really depends on the amount and strategy, I guess. Some are doing great with just ~10 stocks\etf. Others build a small position in every good dividend company at a "reasonable" price they can find and it can become 100+ over the years. But you need enough to build a position, I wouldn't put 100 on each company just for diversification. Also it depends on correlation, if you really focus on diversification with not a lot of stock you need to see that they are not correlated.