AMJ's success and popularity did not go unnoticed. In 2010, UBS and Credit Suisse followed JPMorgan's lead and launched their own exchange-traded notes designed to track these popular companies. Despite their short lifetime, both the UBS E-TRACS Alerian MLP Infrastructure ETN ( MLPI) and Credit Suisse Cushing 30 MLP Index ETN ( MLPN) have already managed to amass relatively impressive volume. Like AMJ, MLPI tracks an index sponsored by Alerian. The Alerian Infrastructure Index is comprised of only 25 firms. Aside from focusing on a smaller pool of firms, MLPI's index is also more sector-concentrated than AMJ. The fund focuses primarily on petroleum transportation, natural gas pipelines, and gathering and processing firms. MLPI's top holdings are also KMP and EDP, though they account for considerably smaller slices than in AMJ. MLPN is unique from both AMJ and MLPI in that it tracks the Cushing 30 MLP Index. Although this index tracks many of the same firms as AMJ's and MLPI's, unlike the Alerian index-based ETNs, the firms underlying this fund's index are equally weighted. The yields for MLPI and MLPN are similar to that of AMJ. All three products carry a 0.85% expense ratio. It is important to remember that, because they are structured as ETNs, AMJ, MLPN and MLPI carry additional credit risk not present in traditional ETFs or equity-backed mutual funds. ETF sponsors are not the only ones attempting to ride the MLP bandwagon. Mutual fund companies have caught on to the popularity of MLPs as well. In early May, SteelPath managed to take MLP investing to a whole new level when they launched a suite of MLP-focused mutual funds which not only provide investors with equity exposure, but also avoids the hassles that come with a K-1 form. The SteelPath MLP Income Fund (MLPDX), SteelPath MLP Select 40 Fund(MLPFX), and the SteelPath MLP Alpha Fund (MLPAX) are set up as corporations, and any distribution is treated as a dividend and reported using the more traditional 1099 form. Despite these funds' attractive tax qualities, investors should be aware that these can be a more expensive option. All three carry a 5.75% front load on top of their expense ratios, although SteelPath says that Class A shares may be purchased no-load on the TD Ameritrade and Schwab platforms, among others, as well as directly online on the Fund's website . The net expense ratios for MLPDX, MLPFX and MLPAX are 1.35%, 1.10% and 1.50% respectively.