Bert, Ernie and Janice decided to invest in the S&P 500 Index. However, each chose a different way to do so. Bert invest in a no-load S&P 500 Index fund. Ernie invested in an S&P 500 Index etf. Janice entered an S&P 500 Index mini-futures contract. Explain the difference between Bert's index fund and Ernie's etf. Is one riskier than the other