THE FTSE 100 index is close to its all-time high.

New share issues, such as Saga, have been making the headlines. Now shares are about to go on sale in one of Scotland's highest-profile businesses, TSB. But is this a time for more caution?

Few investors appear to have followed the old adage to "sell in May and go away until St Ledger's Day" this year. Instead investors are becoming increasingly keen on shares. Hargreaves Lansdown has reported that more investors are transferring out of cash ISAs into the stocks and shares version because of poor interest rates.

Increasing confidence in the UK's economy, rising share prices, and the success of the Royal Mail share offering last year is likely to tempt more people into considering buying a stake in TSB. As an extra incentive retail investors are being offered a loyalty bonus of one free share for every 20 they buy and hold for the first year.

An added attraction for local investors is TSB's high exposure to Scotland. Ed Salvesen, banking analyst at stockbrokers Brewin Dolphin says "TSB is a Scottish brand. It has a higher exposure than any other national bank with 30 per cent of its branches in Scotland. Even the Royal Bank has only 15 per cent exposure to Scotland, Lloyds - excluding TSB but including Bank of Scotland - has 13 per cent and Nationwide 10 per cent."

The new bank will be indemnified from any historical claims coming from Lloyds, such as PPI mis-selling, and has been reported to be benefiting from a £450m "dowry" in the form of vital IT infrastructure.

But there are differences of opinion about what investors should expect from TSB's shares. Mr Salvesen said: "TSB is not a Royal Mail. We do not expect a quick jump in price. And it is not expected to pay a dividend until 2017 unlike other companies in the sector. TSB is on more of a growth trajectory and needs to grow into its branch network first."

At The Share Centre, Helal Miah, investment research analyst, agrees that investors are less likely to be able to make a quick buck out of TSB. He explains: "The difference which investors need to be aware of is that Royal Mail was sold at a discount." Nevertheless, it appears that the price at which TSB is being sold - the exact figure will be announced around June 20 - is relatively modest to ensure a successful float.

However, it is not just the pricing of the TSB offer that investors need to take into account but the state of the market. With the FTSE 100 hovering not far below its all-time high of 6,930 recorded in December 1999, there is always the possibility that the tide could turn at any time. John Blowers, head of investment platform Trustnet Direct, points out: "Investors should be mindful that market valuations are currently very high and if we see a wholesale sell-off, TSB shares will likely get caught up in the move lower along with every other stock."

But Richard Hunter, head of equities at Hargreaves Lansdown, does not believe too much significance should be attached to the FTSE100 Index. He said: "It is inevitable that people will point to the index but it is important to remember that the index does not take account of dividend income and if that had been reinvested, the index would have passed its former high some time ago. It is also important to take into account that the constituents of the index are adjusted every quarter so they are very different today than they were in 1999."

Mr Hunter does not think shares are generally overvalued. He points out that companies have gone through a lot of pain since the financial crisis, they have cut costs and are now in good shape with many producing good growth.

Mr Miah also believes that, while there may be some short term volatility, it is not a bad time to be investing in shares. He said: "The economic data looks good and general confidence is returning, it is difficult to see what could upset the market - but these things cannot always be predicted."

Mr Hunter says share investors need to take the long-term view. He said: "There is always a reason why 'now' is never the right time to invest but timing the market is impossible. It is time, not timing which is important. For example, if you are a long-term investor and you look back at the stock market crash of 1987, it looks like just a blip. The main thing is to invest in healthy companies."

Investing in individual companies, such as TSB, is always more risky than holding a diversified portfolio such a fund or investment trust. If you invest through one of these vehicles you could also diversify your timing by drip feeding your money gradually into the stock market.

One of the cheapest way to get exposure to a whole range of UK shares is through a tracker such as Fidelity Index UK fund which tracks UK share prices and costs just 0.07 per cent a year through Fundsnetwork.