The fund normally invests at least 80% of assets in securities of companies principally engaged in the energy field, including the conventional areas of oil, gas, electricity, and coal, and newer sources of energy such as nuclear, geothermal, oil shale, and solar power. It invests in domestic and foreign issuers. Some companies only facilitate online stock, bond and mutual fund trading; these companies don’t sell their own financial products or offer investment advice. Consumers pay a fee to the company The best no-load mutual fund companies are the ones that have a diverse selection of low-cost, no-load funds. This translates to the companies that offer the best mutual funds with low expense ratios and with no commissions, sales charges, or hidden costs, such as 12b-1 fees.