DeVere Group revealed its foreign exchange division has recorded a "significant upturn" in the number of its clients who are readjusting their portfolio's currency balance, with this trend intensifying since Monday.
It stated that 90 per cent of its trades this week have been out of GBP.
The move comes after last weekend's opinion polls suggested the campaign for independence was now in the lead, having trailed throughout.
James Stanton, deVere Group's head of foreign exchange, said: "It is, without question, the uncertainty over the outcome of Scotland's vote for independence that is fuelling the current flight out of sterling.
"This is unchartered territory and, as such, investors are uncertain about the longer-term economic outlook and financial framework of an independent Scotland and a split union. Therefore they are hedging risk by splitting asset classes, including currencies.
"This is a typical and understandable response in times of uncertainty. However, I expect that this trend will diminish after next Thursday's vote."
Meanwhile another major firm has revealed its plans to move part of its business to England, should Scots vote to leave the UK.
Aegon, an IFP corporate member, has begun establishing a new registered life company in England.
Adrian Grace, chief executive of Aegon, said: "This means irrespective of any currency, regulatory or tax change we can continue to serve all our customers.
"Policies for our non-Scottish customers will continue to be in Sterling and we will support any different currency for Scottish based customers.
"Customers outside of Scotland will continue to be subject to the UK tax regime and will continue to be covered by current regulatory and consumer protection arrangements."