The space for master limited partnership (

) ETFs is about to get a little more crowded on Wednesday with the debut of the Alerian MLP ETF. The ETF will trade on the New York Stock Exchange under the ticker "AMLP." AMLP will track the Alerian MLP Infrastructure Index, which is home to 25 MLPs, including Enbridge Energy Partners (NYSE:

) and Magellan Midstream Partners (NYSE:

). Like the JPMorgan Alerian MLP Index ETN (NYSE:

), AMLP will have an expense ratio of 0.85%. Earlier this year, UBS rolled out the E-TRACS Alerian MLP Infrastructure Index Fund (NYSE:

) and Credit Suisse introduced the Cushing 30 MLP Index ETN (NYSE:

). It remains to be seen if the increase in MLP ETFs heightens volatility for the sector. As the Wall Street Journal put it "some point to ETFs as a catalyst for increased volatility in shares of real estate investment trusts, an asset class to which MLPs are often compared."