In March, confidence was 61, the lowest since January 2005 when the index started, jumping to 96 in May, the highest figure since November 2007.
The index of around 500 HL clients shows an increase in the number of people planning to invest in stocks and shares Isas for the current tax year from 38 per cent to 50 per cent.
The respondents demonstrate a marked increase in their belief the UK stockmarket will be higher in six months, up from 20 per cent to 43 per cent.
The index shows investor recognition that the economy is settling down, with the end of bank losses being reported in the media.
Investment manager Ben Yearsley says: “Confidence was shot to pieces. The financial world was coming to an end and there were so many negative stories in the media about bank losses.”
He believes that a line appears to have been drawn under the crisis, with the series of recent rights issues, designed to improve the situation.
Yearsley says: “The upswing in confidence is likely to have been caused by relief about the banking sector but there have also been a series of decent results recently, such as Sainsbury and BT, helping the general mood that profits can be made over the medium and long term.”