By Roger NusbaumA couple of years ago as the S&P 500 was cascading lower and inducing widespread fear of a new Great Depression, investment-product companies started coming out with absolute return funds in droves. While a modest exposure to this type of product can help manage a portfolio's volatility, loading up on these things after a large decline is the epitome of selling low. Fast forward to today and the S&P 500 has rallied 88% from the March 2009 low and Wall Street strategists seem to be sounding the all clear as they are now debating just how much the S&P 500 will go up in the new year. While I would not advise loading up on absolute return funds, it certainly makes sense to consider adding some exposure now, after an 88% rally. The recently listed Advisor Shares Cambria Global Tactical ETF ( GTAA) could be an effective way to build in this type of exposure. The fund is managed by Mebane Faber and Eric Richardson from Cambria Investment Management. These gentlemen may be familiar to you from their recent book The Ivy Portfolio: How to Invest Like the Top Endowments and Avoid Bear Markets, which outlines the trend-following strategy employed by the new fund. The basic strategy of the fund is to target 31% to equities, 30% to fixed income, 15% in REITs, 14% in commodities and 10% in currencies. There are also sub allocations. For example, 16% of the fund targets domestic equities, 8% in emerging market equities and 7% in foreign developed markets to arrive at the total of 31%. It will build each part of the portfolio using exchange-traded products; mostly ETFs, but also including ETNs and closed-end funds making it a fund of funds with a net expense ratio of 1.35%. The trend-following strategy is simple but historically very effective. A fund can be considered for inclusion in the Cambria ETF if it is above its 10-month moving average. If a fund held by Cambria goes below its 10-month moving average, it will be sold and replaced by a similar fund that is above its 10-month moving average. If no such fund meets the criteria, Cambria will hold cash or short-term debt instruments as part of a defensive strategy. In fact, it is possible that the fund could be 100% cash or short-term debt.