What happened

Shares of CenturyLink (LUMN -0.61%) fell 23.2% in November 2017, according to data from S&P Global Market Intelligence. The company completed its $34 billion buyout of data networking giant Level 3 Communications on Nov. 1, but that was hardly the end of CenturyLink's troubles.

So what

The Level 3 merger was first announced almost exactly one year earlier. The U.S. Department of Justice demanded the companies sell off Level 3's metro networks in three mid-sized markets along with a handful of unused long-range fiber connections. A week later, the two companies published their last earnings reports as separate businesses in the form of a joint filing. The old CenturyLink business saw revenues falling 8% year over year, while GAAP earnings per share dipped 39% lower. The former Level 3 operations held top-line sales steady and increased its earnings by 8%.

CenturyLink's shares fell 5% on the first day of the freshly completed merger, continued sliding through the earnings report, and never really stopped falling in November.

A businesswoman watches a big, red charting arrow plunging down through the floor she is standing on.

Image source: Getty Images.

Now what

Along the way, an unimpressed Citibank analyst said that the merged company was off to "a sub-optimal start with significant hurdles ahead." Several other analysts raised doubts about CenturyLink's ability to maintain its generous dividend payouts. Given that the merger transaction nearly doubled the number of CenturyLink shares, Level 3's healthy cash flow contribution may not be enough to keep the dividend checks flowing. Due to free-falling share prices -- CenturyLink investors have taken a 43% haircut so far in 2017 -- the dividend yield has spiked to an all-time high of 15.3%. Remember, big dividend yields are not always good for investors.