Since I wrote a note about McAfee when they acquired Secure Computing, I thought it would be interesting to point out Symantec's acquisition history. I don't know of any prominent security divestitures, so they aren't like McAfee in that regard, but I can't help notice how often they repeat buys into the same space. This would be fine if it is intended for cheap customer acquisition but that is rarely the reasoning given behind any given acquisition.
Anyway, here is the list:
I can't recall exactly when Symantec bought Axent. Other than that, I think this list is fairly complete.