Investment firm Alliance Trust has said it is setting up companies registered in England ahead of the independence referendum.
The Dundee-based company said it had to remain focused on the service "we provide to all our shareholders and customers across the UK and beyond".
Meanwhile, the boss of insurance giant Aviva said independence was not an issue for him to focus on.
Chief executive Mark Wilson said it was a matter for the Scottish people.
The comments from Alliance Trust came as it announced its annual results.
Describing 2014 as an "important year" for Scotland, the company said the referendum was causing "uncertainty".
Alliance Trust chief executive Katherine Garrett-Cox, said: "After five years of hard work and significant change at Alliance Trust, this year we have started to reap the rewards of that change."
She added: "The referendum in September is creating uncertainty for our customers and our business, which we have a responsibility to address.
"Regardless of the outcome it is critical that we are able to provide continuity of service and protection for their investments and savings."
Ms Garrett-Cox said: "To give them full confidence, we have started work to establish additional companies registered in England, in order to provide operational flexibility and to complement our existing business in Scotland."
Mr Wilson's comments, on Sky News, came after the Aviva chief was asked if he had concerns about an independent Scotland not being able to keep the pound.
He responded: "Obviously we are looking with interest at what's going on, but I really think that's an issue for the Scottish people."
The chief executive added: "We operate all around the world and we operate in many jurisdictions and in many places so I really think that's not an issue for us to focus on."
Scottish Finance Secretary John Swinney welcomed the comments, saying: "As Mr Wilson points out, Aviva already operate in many different jurisdictions, which is the reality for most big companies in today's interconnected world."
Mr Swinney added: "The issues raised by Alliance Trust are entirely addressed by the propositions put forward by the Scottish government, and show exactly why our proposals for a formal currency area are the right proposals, why they are in the best interests of business on both sides of the border and why that is what will be implemented by both governments."
But a spokesman for the pro-Union Better Together campaign, said: "With each passing day the reality of the risks involved with leaving the UK become clearer.
"Yesterday it was Aggreko, the day before it was Shell, Barclays and Lloyds, the week before it was Standard Life. Now we have the Alliance Trust, a firm employing hundreds of people in Scotland and based in Dundee since the late 1800s, warning that it may have to move its business to England if we vote for separation."