Standard Life has been tipped to say an independent Scotland would threaten its business when it announces its annual results next week.
A report in The Telegraph says the insurer and asset manager is concerned that an independent Scotland would be a particular risk for its £97bn pensions business if it were to lose the tax relief paid on UK pensions contributions.
The company has 6 million customers in the UK and total assets under management of £240bn. Although the asset management part of the business would be less affected by a yes vote, analysts say the company would be face a choice of trying to negotiate similar pensions tax relief from a new Scottish government, relocate the business to London or transfer its pensions business to a new subsidiary that remained in the UK.
Last week, all three of the main political parties and Bank of England Governor Mark Carney warned that Scotland would not be able to keep the pound as its currency if it became an independent country.