NEW YORK (ETF Expert) -- Stocks as an asset class have shrugged off a wide variety of risks throughout the year. Sequestration failed to derail equity enthusiasm. The May-June interest rate spike did little to deter dip-buyers.

I suspect that any actual downside for the markets in October, whether caused by political strife or disappointing economic data, will ultimately be viewed as yet another buying opportunity. Indeed, investors are confident that the

Federal Reserve

is looking out for them.

The general trend notwithstanding, several ETFs categories defy a simplistic tip of the hat to the Fed's zero-interest rate policy or its quantitative easing (QE) experiment. In essence, some areas have been rocketing on an entirely different kind of fuel.

So what kind of energy can spark faster price growth than a speeding bullet train from Los Angeles to San Francisco? What sort of propellant might ignite an ETF industry group to leap gargantuan debt ceilings in a single trading session? The answer is "perceived demand." Not actual demand necessarily but a demographic-based perception about future mega-trends.

For example, advertisers on both radio and television covet the all-important 25-54 adult demographic. Someone, somewhere, determined that this classification represents the most important group of consumers. By the same token, these adults with money and jobs are increasingly using social media and/or going online. It follows that, regardless if the valuations of online/net-oriented companies make sense today, the demographic-based perception of social media demand and online activity bolsters Internet ETFs.

I am not suggesting that the perception will last indefinitely. Alan Greenspan, the previous chairman of the Fed, discussed the "irrational exuberance" of market-based securities in 1996. Yet, the dot-com bubble did not burst until 2000. In other words, "new tech" ETF investing may continue winning for a whole lot longer than fundamental value folks would have you believe.

In a similar vein (pun definitely intended), there are plenty of reasons to eschew biotechnology ETFs. Price-to-fair value estimates are unfavorable. Legislative uncertainty presents hazards for pharmaceutical research and development. The current price on many biotech stocks, as well as biotech funds like BBH, are more than 20% above a 200-day moving average; a tendency for stocks to revert to their trendlines would certainly be painful.

Courtesy of StockCharts.com

Whereas the Internet ETFs benefit from a younger demographic (25-54), biotech ETFs benefit from increasing longevity. Not only is most of the wealth in the U.S. controlled by folks who are 55+, but investors perceive those individuals as having the capacity and desire to spend money to prolong/enhance their lives. Here again, a demographic-based perception is fueling investor demand beyond levels that normal valuations might justify.

For my own clients, I have been far more conservative over the last year. I have maintained an overweight towards technology and health care, though I have primarily done so with exchanged-traded funds like

Vanguard Information Technology

(VGT) - Get Report

,

First Trust Technology Dividend

(TDIV) - Get Report

,

SPDR Health Care

(XLV) - Get Report

and

PowerShares Pharmaceuticals

(PJP) - Get Report

. Moreover, it would be awfully difficult for me to recommend the sexier funds in the tables above without a substantive price pullback as well as a rationale beyond the demographic-based theme.

Granted, momentum investors may like biotech and "new tech" right now. As long as those who choose to ride a wave today know exactly when to hop off a surfboard, I see nothing wrong with the initial buy decision. Just make certain to implement a plan for leaving, whether your plan involves

hedges, options or trailing stop limit orders

.

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This article was written by an independent contributor, separate from TheStreet's regular news coverage.

Disclosure Statement: ETF Expert is a website that makes the world of ETFs easier to understand. Gary Gordon, Pacific Park Financial and/or its clients may hold positions in ETFs, mutual funds and investment assets mentioned. The commentary does not constitute individualized investment advice. The opinions offered are not personalized recommendations to buy, sell or hold securities. At times, issuers of exchange-traded products compensate Pacific Park Financial or its subsidiaries for advertising at the ETF Expert website. ETF Expert content is created independently of any advertising relationships. You may review additional ETF Expert at the site.

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