Nexen (NXY on TSX) investors had a big grin on their collective faces this week, on news of a 60% premium cash takeover for their company.

But there was another group of investors, in several other companies, who saw this news as bittersweet. These are investors who owned shares in companies that received nice takeover bids, only to see those takeover bids get drastically re-priced, or, in some case, disappear altogether.

One second—euphoria—the next, lower share prices than even before the takeover bid. Ouch! Let’s look at a few deals in the past little while where investors were left hanging, or were left with a fraction of what they originally thought they were going to get for their shares.

CIC Energy (ELC on TSX): This week’s news that Jindal Steel was to buy CIC Energy for $2 per share might have made a few shareholders happy. After all, the stock rose 13% on the news, and has been below $1 in the past year. However, longer-term shareholders might have been left fuming. Just over a year and a half ago, JSW Energy Ltd. proposed a takeover of CIC for $7.42 per share, cash. Following the deal, the stock was trading close to $7 in early 2011, but the deal collapsed. This week’s takeover is a long way from that price. Sure, markets have been weak, but CIC shareholders are probably left dumbfounded by this rapid change in their fortunes.

Calvalley Petroleum (CVI.A on TSX): Calvalley this month perhaps experienced one of the fastest changes of minds in the market this year. On July 6, DNO International proposed an all-cash $2.30 bid for the company, sending its stock up 79%. Happy days for CVI shareholders. Less than six days later, though, the party ended, and DNO decided it was not going proceed with the takeover. Ridiculous yes, and it was likely only some DNO lawyers who made money off of this one.

But Calvalley shares at least are up over the past year on DNO’s interest. Poor Forsys Metals Corporation (FSY on TSX) shareholders can’t say the same. Going back a little further, Forsys was the subject of a $7 per share cash takeover by George Forrest International in late 2008. It took nine months for the deal to collapse due to lack of financing and other factors. Forsys shares are now languishing at $0.83 per share, 88% below the old takeover bid, and down 42% in the past year.

Compton Petroleum (CMT on TSX) received a $1.25 bid this month from MFC Industrial, a blistering 4% premium to the share price at the time. Compton hadn’t received any bona fide offers for the company prior to this, but the company had been up for sale, more or less, for some time. Shareholders were likely miffed at the small premium, but also rather are likely stunned by their decline in fortunes. Compton stock, one year ago today, was over $20, so this month’s takeover represents a 94% decline from that price (Compton had to do a 1 for 200 reverse split last year). This is a pretty dramatic indication of how bad the oil and gas sector has been over the past year, especially for companies that had a lot of debt. This takeover looks like a done deal, but should serve as a stark reminded to investors of the dangers of debt in a commodity sector.

Looking in the U.S., Joh a Benckiser danced with taking over Avon Products Inc (AVP on NYSE) for a little bit, offering $24.75 per share on April 2nd of this year. Avon didn’t want to dance, however, and the deal was terminated a month later. Avon shareholders are now 37% under water from the takeover price, and down 43% in the past year. Shareholders might need some makeup foundation to cover up their tearstains on this failed deal. What is the lesson here? Well, maybe this: When you are fortunate enough to own shares in a company that receives a takeover bid, maybe you should sell at least part of your holdings. Sure, every so often there is a competing, higher bid. But there is also the real possibility of a complete collapse. Don’t take a gift and then be left holding the bag.