Few energy stocks have been hotter of late than SemGroup (NYSE: SEMG), which has returned 20 percent since we added it to the Growth Portfolio on May 16.

The gains followed an early June acquisition of 124 Chesapeake Energy (NYSE: CHK) crude trucks, expanding the gathering footprint of SemGroup’s sponsored Rose Rock Midstream (NYSE: RRMS) MLP beyond North Dakota and Colorado into Texas, Oklahoma and Ohio.

On June 23, after announcing the dropdown of the remaining third of its interest in a crude pipeline subsidiary to Rose Rock, SemGroup and its affiliate raised their annual profit and distribution targets, citing “the impact of recent acquisitions as well as higher volumes on its existing business.” And while the 5 percent bump in an EBITDA forecast following an acquisition is hardly a home run, investors were buoyed by news that SemGroup’s modest dividend would rise 40-45 percent this year, instead of the previously promised 25-30 percent.

Rose Rock, in turn, is now aiming for a 25 percent distribution increase in 2014, up from prior guidance of 15 percent. By recent standards, its current yield of 4 percent is relatively generous given that growth rate.

We continue to see SemGroup’s crude logistics and gas processing assets as an excellent play on the North American drilling boom and on investors’ ravenous appetite for both yield and growth. While a period of digestion may be in order soon, the valuation remains attractive relative to the growth rate. Buy SEMG below the increased target of $82.