Large caps gives stability and liquidity . This kind of filter is for us to deep dive further . For example , AMZN will not fall as the NPM is less than 10 %, but a good company . Newbies should definitely start using these as they need initial stability to learn , otherwise they stand to loose entire amount . Personally , I start focusing above 300 M cap companies , but mostly prefer above 1 B . The reason for 1 B is stability in management as startups are always having management issues , easy firing and hiring . However , good growth are in MID Cap 2 B 10 B or Some Small Cap 300 M . However , Seth Klarmann says that we can find hidden treasures in unknown small caps . It all depends how much we research on each company and our comfort to invest in such companies . For example , I have $ WVVI very small cap of 40 M . My gain in $ VEEV is better than $ AMZNIn short , starters need to focus on Mediumtolarge caps to avoid pitfalls until they learn . For experienced people , there is no limit as it depend on their research and comfort .