We’ve all heard the advice about not keeping all your eggs in one basket. This is the principle that stock diversification is based on: for example, not putting all of your money in one sector, such as financial services. If that sector were to crash, you could lose a lot of your money.,We’ve all heard the advice about not keeping all your eggs in one basket. This is the principle that stock diversification is based on: for example, not putting all of your money in one sector, such as financial services. If that sector were to crash, you could lose a lot of your money.