It's merger Monday! Almost. Pipeline giant Williams Cos. Inc. (NYSE:WMB) announced on Sunday that it will "explore a range of strategic alternatives" after receiving -- and rejecting -- a $48 billion takeover offer from a suitor that turned out to be Energy Transfer Equity LP (NYSE:ET). That's the sort of new that can get traders' animal spirits going, and stocks are starting the week on a positive note with the Dow Jones Industrial Average (DJINDICES:^DJI) and the broader S&P 500 (SNPINDEX:^GSPC) up 0.66% and 0.69%, respectively, at 12:20 p.m. EDT. The technology-heavy Nasdaq Composite was up 0.67%.

Although Energy Transfer's all-stock offer valued Williams at $64 per share, nearly a 33% premium to the shares' closing price last Friday, the target said its board "determined  that it significantly undervalues Williams and would not deliver value commensurate with what Williams expects to achieve on a stand-alone basis and through other growth initiatives, including the pending acquisition of WPZ [William Partners LP (NYSE:WPZ)]." 

Energy Transfer's offer was conditional on the termination of Williams Cos.' offer to acquire the remaining equity of Williams Partners it does not already own (roughly 40%). 

Not content with an empty critique of Energy Transfer's offer, the Williams Cos. board got specific regarding what investors should look for "on a stand-alone basis," stating it expects "the growth of our business and the benefits from the WPZ transaction to enable 10-15% dividend growth through 2020." 

In light of Williams' track record, that goal appears quite achievable: Over the 10-year period through 2014, Williams increased the annual amount of dividends per share by an annualized rate of 37.7% -- a phenomenal result.

Williams operates a pipeline network spanning 33,000 miles in North American (the company transports 30% of America's gas). Those assets are very difficult (impossible, in fact) for a would-be competitor to reproduce: Williams has a durable competitive moat, which produces extra-normal returns on behalf of it shareholders. 

Energy Transfer might not ultimately take home these prize assets, but Williams is "in play," and investors should expect more mergers and acquisitions activity from the entire pipeline sector in the coming months.

Greece: Are we there yet?
Every week for the past month, it seems like we've been told that this is the "last chance" for Greece and its creditors to patch together an agreement to avoid default and, possibly, Greece's exit from the eurozone. There are some hard markers, however, including a €1.5 billion payment due to the International Monetary Fund at the end of this month, which Greece is unlikely to make without some form of aid. 

Eurozone members' heads of state will meet on Monday evening to discuss the "Greek question" at a hastily arranged summit -- heads of state have now taken the football from finance ministers.  Traders are optimistic: the Global X FTSE Greece 20 ETF (NYSEMKT:GREK) was up over 8% at 12:20 p.m. EDT, but success is not assured. If nothing substantial comes out of this evening's meeting, expect volatility to rise this week, particularly in European markets.