NEW YORK (TheStreet) -- When cheap money is flowing, bad deals are inevitable. With merger activity dominating the headlines recently, we took a look at past mergers to come up with a list of the five worst mergers of the last five years.

To find the stinkers, we looked at more than 100 mergers, paying particular attention to those that garnered big headlines. We then looked to see how quickly these mergers resulted in write-offs for the acquiring companies. The results amazed even me -- both at the size of the write-offs on some, and how quickly the write-offs occurred. Perhaps companies need to step back and look at past merger-failure rates before firing off new buys.

1. Hewlett-Packard & Palm

Not surprisingly Hewlett-Packard (HPQ) leads the list of worst dealmakers -- with two notable stinkers over the last five years.

First off we have the disastrous Palm acquisition by Hewlett in April 2010 for $1.2 billion. Analysts and traders cheered the deal at first as a way for Hewlett to catch up in the mobile market dominated by Apple (AAPL) and Google (GOOG). A sex scandal with CEO Mark Hurd resulted in his firing a few months later and new successor Leo Apotheker decided Palm was not part of his strategic plans. After plowing an additional $2.1 billion into webOS, Hewlett wrote off the $3.3 billion investment in December 2011.

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