I love Monday mornings for the sole reason that they are often very exciting from a merger announcement prospective. Many have expected lots of merger and acquisition activity in the energy sector but until today there was very little going on there. With this morning's announcement that ExxonMobil (XOM) is buying XTO Energy (XTO) it appears that the long anticipated trend of consolidation in mid-sized North American energy companies (most notably the unconventional natural gas producers) may be under way.

Exxon is paying a 25% premium for XTO Energy, one of the five companies always rumored to be on the short list of possible major oil company targets. Exxon is a conservative dealmaker so the fact that they are shelling out $31 billion ($41 billion including debt assumption) for XTO shows that they not only liked what they saw and the price they got. Other leading oil giants (think the likes of BP and Shell) are likely scrambling to draft their own plans to follow suit to ensure they do not get stuck with inferior growth properties. The majors are lacking an excess of replacement fields for the huge amounts of energy they produce each year, so a large acquisition is really the best way to secure future growth opportunities in a very competitive energy market.

So who might be next? I have compiled a list of the obvious targets, including valuations, to show you exactly why Exxon likely chose XTO (it was the cheapest company in the group), what other firms are likely going to have their tires kicked in coming months, and which of the remaining independent firms may be most attractive from a price tag perspective. Exxon is paying 6.6x trailing cash flow for XTO, so we can expect that to be the yardstick off of which future deal negotiations will be based.

Full Disclosure: Peridot Capital was long Chesapeake and Devon at the time of writing (yeah, unfortunately no XTO) but positions may change at any time.