If both indices are equal to or greater than 95% of their opening levels at maturity the full return of 21% will be paid.
Capital protection is in place unless the final level of one or both of the indices is below 60% of their opening level.
The minimum investment into the plan is £10,000 and it is available as a direct investment or through pension funds.
Graham Devile, managing director of Meteor, said: "As investors continue to reassess their risk appetite, they are searching for growth in less volatile structures and underlying assets.
"We believe the 3 Year Defensive Growth Plan offers familiarity of the FTSE 100 and S&P 500 and should appeal to investors who are looking to balance risk with potentially enhanced returns over the shorter term in what is arguably a subdued market."
