That’s what one Wall Street analyst writes following Pfizer’s not-so-exciting briefing for big investors last week. In her 77-page report, Credit Suisse analyst Catherine Arnold argues the dividend, which offers a handsome 5.8 percent yield, may be in danger due to the soon-to-expire Lipitor patents. And to maintain the payout, Pfizer may have to repatriate off-shore cash, driving up its tax rate.

Here’s why: Lipitor contributed 65 percent of Pfizer’s free cash flow last year. This is an issue, you see, because the dividend can only be paid from US funds. Repatriation rules, she notes, prohibit the transfer of offshore earnings to the US without generating a tax liability. And as Lipitor patents begin to expire in 2010, cash flow starts to shrink - to less than 30 percent in 2011, according to Arnold. At the meeting, Pfizer execs talked about continuing the dividend “at least at current levels.”

Arnold’s take? “Assuming historical levels of dividend increases (10 percent annually), Pfizer’s free cash flow will fall to less than the dividend by 2013. This calls into question the sustainability of Pfizer’s dividend (and dividend increases), and therefore of the stock price which it underpins…In order to maintain historical dividend increases, or even maintain a flat dividend, we think Pfizer will need to repatriate some offshore funds, which will trigger a tax liability and reduce net margin. Even if Pfizer is able to maintain its dividend – that is, if the dividend is not at risk of a cut – we think this will come at the cost of a repatriation tax liability, which will pressure earnings.”

Either way, investors aren’t going to be thrilled. So Arnold uses this to support her argument that, despite Jeff Kindler’s pronouncement that no big deals will be done, Pfizer ought to consider a deal - and she points to Wyeth or Amgen. In fact, Arnold has been pushing a Pfizer-Wyeth combination for a year now. Credit Suisse, by the way, makes a market in Pfizer stock and wants to do investment banking for the drugmaker.