Savings accounts for big balances rarely remain best-buys in the long term, according to Investec Private Bank.

Research from Investec showed only 3 savings accounts for balances of £25,000 or more that were top 10 best buy deals during the 3 months to 27 January 2007, still held best buy positions during the three months to 27 October 2007.

It also found the average rate of interest for balances of £25,000 during both periods was 3.43% lower than that for accounts with balances of £1. As a result, Investec revealed that a saver with a £25,000 balance could be missing out on approximately £857 in interest per year.

Linda McBain, spokesperson for Investec Private Bank, said: “Savers should look beyond the headline rate when selecting a savings account as they often include bonuses, which once expired, can mean a significant drop in the rate paid.

“With the base rate currently relatively high, it is even more important that consumers get the best possible rate for their savings and that they choose an account that has consistently paid an attractive return, or one that promises to do so. Our analysis shows that just 4 out of 10 accounts for high balances remain best buys nine months later.”