According to research firm Dealogic, the M&A market is in a big-time downward spiral. For November, the U.S. market saw a 71% drop in deal values to $58.1 billion.

If history is any guide, the M&A market is a feast-or-famine business, and the transition can happen fairly quickly.

Of course, a key factor is the credit crunch. It takes gobs of debt to get deals done, especially for private equity. Also, with an uncertain economy, strategic buyers may also be holding off – even if the valuations look compelling.

Interestingly enough, five of the top 10 deals in November were from foreign-based buyers. With sovereign funds bulging with U.S. dollars, the trend should continue. Although, some of the latest deals have been minority investments, such as the $7.5 billion Citigroup (NYSE: C) transaction from Abu Dhabi Investment Authority.

However, without the juice from private equity, it's hard to make a case for a strong 2008 (the average deal size was a measly $127 million in November). So, for M&A dealmakers, they may want to be thinking of getting another career.

Tom Taulli is the author of various books, including The Complete M&A Handbook and The Edgar Online Guide to Decoding Financial Statements. He also operates DealProfiles.com.