The chief executive of Alliance Trust says there are many questions but "very few answers" about the Scottish independence referendum as the investment giant hailed the globalistion of its revamped portfolio for an improved performance.

Katherine Garrett-Cox said the board and senior management were discussing the potential implications of the referendum.

She said: "As a Scottish company we would be remiss if we weren't.

"There are lots of questions but very few answers so we will be keeping a watching brief."

Dundee-based Alliance Trust yesterday announced its net asset value per share was 495.6p in the first six months of the year. That gave a 12.5% total return and was ahead of the 11.1% reported for the AIC Global Growth Sector.

Alliance Trust was ranked 11 out of 35 using the AIC metric for the half-year and at number 12 out of 34 over 12 months.

Ms Garrett-Cox said she was pleased with that performance and signalled there would be a 47th consecutive increase in annual dividend.

During the period Alliance Trust built positions in Walt Disney, shale gas provider Noble Energy, US-based robotic surgery business Intuitive Surgical, Japanese bank Mitsubishi UFJ and UK insurer Resolution.

The largest holding in the portfolio, which was slimmed down from 450 stocks to around 100 last year, was pharmaceuticals giant Pfizer with Alliance's stake worth more than £73 million.

Others in the top ten including Samsung, HSBC and Prudential while Alliance Trust also has stakes in the likes of Diageo, Google, Apple, Royal Dutch Shell and Unilever.

Ms Garrett-Cox believes the current volatile nature of equity markets will not necessarily be detrimental to performance.

She said: "In a funny sort of way fragility and uncertainty are opportunities for us as we are looking for good sustainable businesses that will perform whatever the weather.

"We have this constant search for capital gains and companies which can pay us good dividends.

"We are confident in the companies we are holding and are taking a five years plus view."

Dividend income between January and June this year was £53.8m, up from £50.3m in the same period during 2012.

Asked whether the markets would benefit from more guidance on when measures such as quantitative easing would be withdrawn she said: "I feel it is a really stop start economy around the world where a piece of good news is followed by a piece of bad news. Central bankers are really walking a tightrope but we believe in the next six to 12 months there will be some clarity provided [on money stimulus]."

Ms Garrett-Cox said the results from other parts of the Alliance Trust business were also encouraging.

The savings arm reported a £200,000 operating profit in the period with assets under administration close to £5 billion.

The profit did not take into account a £5.2m gain on the sale of its Self-invested Personal Pension (SIPP) to Bristol-based Curtis Banks or around £1m spent on marketing about the retail distribution review of independent financial advice.

Meanwhile third party assets under management at Alliance Trust Investments were up £100m to £1.5bn and losses narrowed from £2.7m to £1.7m.

Ms Garrett-Cox did not rule out share buybacks in the future but suggested Alliance Trust's current performance made it less likely that tactic would be used.

She said the discount – how much the share price is behind the net asset value – has narrowed in recent years and added: "Rather than buy shares and shrink the size of the business we would rather invest the money in companies which could give us a return."

Low borrowing rates saw gearing in the period go from £200m to £340m with the additional funds invested in equities.

Shares closed down 4.5p, or 1.01%, at 441.5p.