A Scottish vote for independence from the United Kingdom this month could have serious consequences for the Scottish and U.K. economies, Goldman Sachs said in a research note on Wednesday.

Goldman Sachs economist Kevin Daly said that while the Wall Street bank still felt the most likely outcome was for Scotland to vote to stay in the United Kingdom, a surprise victory for the "Yes" campaign to break away would have a drastic impact.

"Opinion polls suggest that the gap between the 'Yes' and the 'No' camps has narrowed but that a 'Yes' vote in favour of independence remains unlikely," Daly wrote in the note.