Whenever a company pays out dividends, they reinvest them in more stock rather than send them to you.
Like most other Facebook games, you have the option to reinvest your earnings into growing the profitability of your farm through expanding it with more room for farming or you can opt to decorate your farm.
Making small profits in the beginning allows you to reinvest portions of your income into company growth, rather than using your personal savings.
Reinsurance makes it possible to offer more coverage and brokers deal with each plan (or group of plans) to reinvest and make things profitable.
The final step is to reinvest your money once the bonds have reached maturity or stopped paying interest.