Although the energy sector is prone to booms and busts, it can spend years between those extremes and sometimes months without doing much, belying a well-deserved reputation for volatility.

We’re now in one of those lulls, with oil prices rangebound at $40-50/bbl since May and most energy equities also going nowhere fast since the nifty springtime rally.

There have been notable exceptions, of course, as subscribers who followed our recommendations of coal miners Consol Energy (NYSE: CNX) and Alliance Resource Partners (NYSE: ARLP), renewable energy dividend play TerraForm Power (NASDAQ: TERP) and shale driller Apache (NYSE: APA) can attest.

But the sector on the whole has been marking time while waiting to see whether $50 oil can form the basis of a new market equilibrium. In pushing for the recent OPEC deal to curb output, Saudi Arabia confirmed what the market still hasn’t priced in: that the kingdom is not-so-slowly going broke at that price after accounting for all of the billions it spends on social programs.

One way or another, it will all work out over time. Either the young and fast-growing Saudi population will accept unprecedented but inevitable benefit cuts or it won’t and oil prices will zoom higher as a consequence of the resulting instability. The only certainty is that U.S. shale producers will step up drilling in the months ahead as a result. Their aggressive selling of crude futures to hedge planned output gains is the main reason prices didn’t risen more in the wake of the surprise OPEC agreement.

That makes us more bullish on U.S. crude producers, especially some of the smaller and more speculative ones we’re researching for possible portfolio inclusion in the weeks ahead.

But we continue to believe that some of the best current energy opportunities are to be found in the midstream sector, which makes the bulk of its money on volume regardless of the prevailing energy prices.

Of course the current Alerian MLP Index yield at a bit over 7% can’t compete with the 10% available eight months ago. But much of the downside risk has dissipated in the interim as well, while some growth opportunities inconceivable back then are now looking good once again.

The next meaningful move in MLP unit prices is likely to be up, and in the meantime the only thing better than a 7% yield is a 13% one.

That’s why we’re adding the ETRACS 2xMonthly Leveraged S&P MLP Index ETN Series B (NYSE: MLPZ) to the Aggressive Portfolio. As the name suggests, the MLPZ is designed to double the monthly gain or loss of its underlying index. The leverage means it yields twice what the index does as well, less the issuer’s annualized 0.95% fee.

The MLP sector’s fundamentals are improving, and we are nowhere near another major downturn like the one that befell it last year.

As an added bonus, the S&P MLP index tracked by the MLPZ includes, in contrast with the Alerian MLP Index, Energy Transfer Equity (NYSE: ETE), which happens to be our top-ranked Best Buy. ETE’s 11% weighting in the MLPZ comes at the expense of other large MLPs over-weighted by the Alerian.

Aggressive investors should buy MLPZ below $60. As always with speculative investments, do not overweight your money in any single position.