However John Haynes believes any effects on share prices will be short lived and "not very pronounced".
Mr Haynes, in Scotland to meet clients, said the group he worked for had not yet agreed upon any likely outcomes on the referendum but indicated the market expectation was that things would not change.
He said: "The process of getting to that vote may raise stresses in the market. [It] is a very difficult question and we have we not come to a consensus with our asset allocation committee about what we should do about [the referendum].
"My jury of one verdict on this is that we will see some nervousness in the UK markets as the referendum day approaches and the noise goes up but it will be temporary and not very pronounced."
Mr Haynes, who heads a 19-strong research team in London, did acknowledge that unexpected events could take place close to major votes, which could "change the maths".
On a UK level he does not expect interest rates to rise this year while markets would expect the Conservative and Liberal coalition to "be rewarded" for charting a course towards fiscal stability with a second Westminster term from next year.
He maintained that UK equities were a "little less" attractive than overseas equities going in to 2014.
Instead he believes emerging markets, particularly in China, offer very attractive investment prospects while parts of Europe are looking "surprisingly" strong and the US appears to be building momentum. He said: "Emerging markets have not yet had the good effects of America getting better; Americans spend money when they feel good so demand starts to come out."
According to Mr Haynes negative forces such as restructuring in Europe and voluntary easing of growth in China are less likely to re-occur this year.
He said: "We think people are discounting the possibility of not just a better set of headwinds but the fact that when the US and Europe get back to the party then you get a bunch of demand. "For me this is not the time to be getting frightened by emerging markets."
Mr Haynes pointed out that the explosion in middle class consumers expected over the next 15 to 20 years was likely to come from Asia.
He said: "Regionally we have a concept that we like quantity consumers rather than quantity producers. Broadly we think the development of consumer societies within these economies is what needs to happen.
"That is much less a heavy industry oriented opportunity [so] the intellectual property producers - India and China - are more interesting to us than the raw material suppliers like Russia and Latin America."
He also expressed an interest in how economies in Africa are starting to grow and the way technology, particularly the internet, is making it easier to start-up and grow businesses around the world.