Let's first point out that there is absolutely no indication that UCP would want to achieve a OMX listing. There are some good, rational, reasons why it could benefit from a listing overseas, but similarly there are also good reasons why they should invest more energy into shareholder communication - and still they don't ;-)
Next, OMX is not an exchange. It's a quotation system equivalent to the OTC (which is also not an exchange).
However, if they chose to go for OMX, there are two basic routes
a) Dual listing: The simple route. Many companies are traded on different exchanges / quotation systems simultaneoulsly to increase public exposure and liquidity. The company would apply for trading on OMX AND maintained its status on pinksheets. Nothing would change for you except that you had the option to also buy / sell shares in Scandinavia if your broker supports that. The company would remain incorporated in the US.
b) Single listing in EU: If the company wanted to give up its US- public listing altogether, things are getting a bit more complicated as they might have to re-incorporate the business locally in Sweden.
Once accepted for trading by OMX, the company would then be given a new Cusip number or equivalent identification and shares would be exchanged by your broker in a similar fashion as if a new firm merged into a shell. Shares would normally be exchangd one-to-one. Not sure if the company can be forced to make a buy-out offer to shareholders that don't want to own shares in a, then, foreign, company.
As usual in pinkieland: If a company wants to play fair, they can play fair. If it wants to play foul, the can play foul.
News 
Market Data 
Discover 
