Near the end of a turbulent week, Marc Faber, a.k.a. Dr. Doom, made headlines when he predicted a sharp sell-off in the second half of the year. In a recent interview, Faber announced to the public that he believes the U.S. stock market is drastically overvalued and due for a correction of at least 20% this year. Faber is famous for predicting steep market sell-offs, including the 1987 and 2008 drops.

Despite what you may think of his view, it never hurts to have a game plan in place for a sell-off. I would like to offer three exchange-traded funds you may want to consider moving into before a nasty pullback. The following options all have major tailwinds over the long term and should perform well, even amid a bond-market debacle. 

84.5 is the new 30?
The secret is out: Our population is aging here in the United States. We are living longer than ever, as access to advanced medicine has allowed many to overcome the traditional pains of aging. As a result, investors and analysts alike have become increasingly bullish on much of the health care space. One industry in particular, health care services, has done especially well. The SPDR S&P Health Care Services ETF (XHS 0.84%) is up by more than 35.5% over the last year.

The National Research Council recently put out a report in which it attempted to estimate the extent of the trend. The report predicts that by 2050, average life expectancy will rise to 84.5 years -- almost seven years longer than we are living today. The fund offers investors easy exposure to health care companies specializing in everything from supplies to insurance to staffing. Due to the increase in life expectancy, it's natural to predict great strain on the health care sector. Interest-rate volatility may wreak havoc on the older investor's portfolio, but I doubt it will have much of an effect on the demand for medical care. I would be using a 20% drop in the broad stock market to pick up some of this ETF on sale and hold for the longer term.

Financial success
While rising interest rates may seem painful for some sectors, the financial sector stands ready to reap the rewards of higher rates. The entire sector has soared already this year; everyone from the big guys to the regionals and the mortgage insurers have done well, as exuberance from the Street has pushed everyone into the sector. The Financial Select Sector SPDR ETF (XLF 1.29%) has risen 20% since the start of the year as its top three holdings, JPMorgan Chase, Wells Fargo, and Berkshire Hathaway continue their dominance in the financial space.

Berkshire Hathaway in particular reported a strong second quarter, with profit of $4.54 billion, or $2,763 per class "A" share, versus $3.11 billion, or $1,882 per share, in the second quarter of last year. Revenue climbed 16% to $44.69 billion, thanks to top-line growth at its insurance operations, railroads, utilities, and energy businesses.

Interest rates have sunk to generational lows, making it tough for many financial institutions to turn a profit. Over the last few years, banks were forced to become lean and mean through extensive cost-cutting measures. However, as interest rates rise, the spread at which the institutions can borrow and lend widens, thus generating higher net-interest margins. I would take advantage of a 20% pullback and step into the sector if I had missed this year's run-up so far. A multistage bull market within the financials seems likely as credit quality improves with rising interest rates -- the so-called "perfect storm."

The broad basket
As the market makes all-time highs in the face of tightening monetary policy, some investors may be looking to cash in on unrealized gains.

However, if we are lucky enough to get the 20% pullback Faber is calling for, investors need to realize that it's a huge buying opportunity for the longer term. Sure, it would look nasty on your monthly statements, but you must recognize the opportunity. The Great Depression, the crash of 1987, and the 2008 financial crisis were all buying opportunities within the broad market, and just as there will always be pullbacks, there will always be rallies. Don't be afraid to start buying when everyone seems to be selling.

I will be using any sharp drop as an opportunity to add to my positions within the health care and financial sectors. I understand there are many different exchange-traded funds that offer similar exposure, but I favor the SPDRs. These funds tend to be the most liquid, whereas some of the smaller funds can get distorted during turbulence. For example, the SPDR S&P 500 ETF (SPY -0.49%) offers investors the broad market exposure I have talked about -- and for a measly 0.11% in management fees. This highly liquid ETF makes hedging simple in the options market.