Investors with the stomach for gas futures will want to keep a close eye on the weather patterns throughout the winter. Dramatic changes can heavily impact the fuel's performance. Market Vectors Vietnam ETF ( VNM) -3.0% The volatility of frontier and emerging markets can be seen by looking at this week's day to day fluctuations in the Vietnam ETF. While VNM scored some of the strongest gains across the ETF universe on Monday, on Tuesday the fund is a noticeable decliner. iShares MSCI Austria Investable Market Index Fund ( EWO) -0.3% Despite the domestic market's strength, the European sovereign debt crisis continues to rage, pressuring ETFs designed to track the most vulnerable members of the currency bloc. While many have focused on nations such as Portugal, Ireland, Greece, and Spain, Austria may have issues in the near future. Europe should be approached with extreme caution going forward. All prices as of 2:15 PM EST Written by Don Dion in Williamstown, Mass.