NEW YORK ( TheStreet) -- BlackRock, the largest U.S. asset-management firm, says Americans need to consider different ways to ensure they have enough money in retirement, including reducing cash holdings and using exchange traded funds. The stock market has been volatile, making investors skittish. Yet Treasury yields at 2% are barely keeping up with inflation, and there is a lot of cash on the sidelines earning almost nothing. That has left many investors discouraged. 10 Top Warren Buffett Dividend Stocks "Investors are looking for answers in a new world where the returns they once took for granted are constrained by historically low yields, market volatility and shifting investment patterns," BlackRock CEO Laurence D. Fink said. "Wherever I go, the question I hear most often is: 'So what do I do with my money?' " So as an investor, what should you do? BlackRock suggests making your portfolio more dynamic -- it needs to be flexible enough to adjust to quickly changing market conditions and diverse enough to take advantage of global trends. In its new multi-media approach, called "Investing for a New World," BlackRock provides these five considerations to ensure you have enough money in retirement. 1. Rethink the Cost of Cash Holding some cash is prudent, but given inflation rates, cash will lose nearly half of its value over a 20-year retirement. Long-term investors need more robust strategies to preserve the value of savings. 10 Mid-Cap Stocks That Have Almost Doubled in 20122. Seek Income in Different Places Consider investing in dividend-paying stocks, which often pay twice as much as Treasuries. Higher yields can also be found in corporate bonds, high-yield bonds, municipal bonds and even emerging market sovereign debt. 3. Open Your Eyes to Alternatives Alternatives like mutual funds and exchange traded funds that invest in commodities, real estate and energy can achieve above-average returns and reduce risk because they are less likely to move in tandem with stocks and bonds.