There were few investment professionals who believed in exchange-traded funds (ETFs) back in 1993. In fact, you could count the early adopters on your keyboard-using fingers. For example, my friend and money manager Tom Lydon used ETFs before he created ETF Trends. Dave Fry gathered a following at ETF Digest. And “yours truly?” I regularly discussed the benefits of  “SPY” and “QQQ” on financial talk radio across 70 or more affiliates around the nation.

In the 90s, ETF that tracked popular indices like the S&P 500 or NASDAQ 100 were not without their charm. They provided diversification with lower costs, greater tax-efficiency and total transparency. On the other hand, Vanguard’s suite of index funds offered the identical perks. And since buy-n-hold had been the predominant investing approach at the time, the desire for a diversified asset that traded throughout the day was skimpy at best.

Of course, the tech wreck (2000-2002) and the financial collapse (2007-2009) went a long way toward changing perceptions. Liquidity at a desirable price point became more important for managers of risk. By the end of 2009, nearly 1,000 exchange traded vehicles existed on the U.S. exchanges alone. In October of 2015? The $2.1 trillion industry has 1700-plus products and continues to grow, whereas the $12.9 trillion mutual fund business continues to lose assets under management.

Why am I bringing up the evolution of ETFs/ETNs? In essence, our late-stage bull market is favorable for the original game-changers – S&P 500 SPDR Trust (SPY) and PowerShares NASDAQ 100 (QQQ). You might own them as part of your current stock exposure. On the flip side? If you commit significant financial resources to any of the other 1700-plus ETFs in this investing environment, you may get burned.

In spite of CNBC’s enthusiasm for the superb October stock rally of popular benchmarks like the S&P 500 and the NASDAQ, very few companies are responsible for the success. Breadth remains extremely weak. In fact, one can look at an equal-weighting of S&P 500 components via Guggenheim S&P 500 Equal Weight (RSP) and compare it with the market-cap weighted SPY. When you do so with the RSP:SPY price ratio, one sees just how poorly individual companies are performing relative to heavily-weighted components in SPY (e.g., Facebook, Apple, Microsoft, etc.).