What: Shares of TECO Energy, Inc (NYSE: TE) are up more than 24% today, on news that it will be acquired by Canadian utility Emera, Incorporated. The deal will pay TECO Energy shareholders $27.55 per share in cash once it closes. 

So what: After today's price jump, TECO shares are trading at just over $26, still a bit below the sale price, so there's still some money on the table. This is relatively typical for a deal like this, which isn't expected to close until the middle of next year. The current market price is about a 6% discount to the amount Emera will pay when the transaction closes, not including the roughly $0.68 in dividends it will pay over that time.

There are a few considerations that investors need to make before taking any action, however. 

Now what: To start, when you factor in the dividends expected to be paid over the next 10 months or so, that puts today's stock price at roughly a 9.3% discount in total returns to the deal price. There are a lot worse things to do than capture essentially 9% in almost guaranteed returns by holding at least through the last dividend before closing.

Furthermore, if you hold your shares in a taxable account and have held for less than one year, it's really worth considering holding until you get past that one-year point, in order to lower your taxes due from your marginal income tax rate to the 15% or 20% capital gains rate. In addition, as time passes, the trading price of TECO stock should inch up, getting closer to the $27.55 per share as the closing date of the deal approaches. While there is some risk in waiting -- mainly that shareholders don't approve the deal early next year and the price falls -- that's not likely a very high risk at this stage. 

Just to summarize, there's 9% in relatively predictable upside still on the table for investors, whether you own shares already or not, between the remaining dividend payments before the transaction is completed and the current discount on the stock (the difference between today's market price and the closing price when the deal is complete). Current shareholders, and investors looking to grab some relatively secure gains, could do worse than holding, or picking up some shares and holding until the deal is done, with the caveat that the deal falling apart would likely lead to some small losses.

It's up to you to decide if that small risk is worth the upside or worth avoiding.