Demand for ETFs continues to grow at a rapid pace, and large firms like Vanguard, Schwab ( SCHW), State Street ( STT) and Fidelity will all likely offer similar lines of proprietary ETFs in the not-so-distant future.State Street and Vanguard are already well into the process, and Schwab recently announced the launch of its own proprietary ETFs to join the pack. Large firms are racing to grab a slice of the ETF business and BlackRock's ( BLK) recent purchase of the iShares ETF product line upped the ante. As a new swell of ETF products hits the market, the pressure is on for investors to understand what they're getting and for issuers to understand the role that ETFs will play. The dawn of the ETF industry brought transparent, passive indexing strategies, designed to give investors access to sectors at a lower fee than mutual funds. As the ETF trend caught on, ETF issuers rapidly expanded their product lines, offering increasingly focused strategies. Products were launched by the dozen and the market contraction in 2008 finally began to pare down their ranks to the most viable funds. Today, issuers are more conscious of the role that ETFs can play for the larger investor community. As the bubble of aging baby boomers looks toward retirement, ETFs are trying to swipe business from mutual funds with target-date ETFs and actively managed ETF products. Fixed income and commodity products have drawn swarms of investors, who may not understand the flaws of some products before jumping in. As more issuers enter the ETF arena, the temptation will be to do too much at once. Existing issuers have tested the investor audience and new issuers should take a hard look at the funds that have failed before launching their own methodologies.