Is your Isa invested in a "dog" fund? The fund, managed by Tom Dobell, invests in shares that have been out of favour with investors for a number of years, described as so-called "recovery stocks." But Bestinvest said the fund manager has made series of wrong calls, failing to pick the UK shares that are benefiting from Britain's economic recovery. "Funds from leading manager M&G have seen the level of dog assets swell from £13.3bn in July 2013 to a mighty £22.3bn today," said the report. Poor performance was most evident across the £3.8bn M&G Global Basics and £7bn M&G Recovery fund, the latter has had a traumatic 18 months - underperforming its peer group by almost 20pc. A spokesman for M&G defended the fund's performance. While these funds have had a challenging last few years they are managed for long term performance, and we ask our clients to take a similarly long term view. The dogs are highlighted by close analysis of past performance. This means comparing them against their benchmark, which is an index representing the overall movement of the specific markets where the fund manager invests. A fund will qualify as a dog if it has lagged 10pc below the benchmark every year for the past three. This strips out the funds that have "simply had a short run of bad luck," Bestinvest said. The worst UK fund was Manek Growth, which has turned £10,000 into £6,200 in three years. In second place was Ignis UK Focus, turning £10,000 into £10,400, followed by F&C UK Alpha, which has turned the same sum into £10,800. In contrast, crowned "best of breed," the Liontrust Special Situations fund has turned £10,000 into £15,800. The report highlighted that US funds were the worst performers, with 22pc of dog assets in these funds. The worst performers named include Investec American, Cavendish North American and Allianz US Equity. Jason Hollands, a director at Bestinvest, said savers should monitor their investments closely to ensure they are getting good value for money. Our message is simple: no matter how thoroughly you researched your choices ahead of investing, the fate of funds can change over time as the appearance of three previously popular and once strong performing M&G funds illustrates. If you are going to invest in funds, particularly those which are actively managed, then it is vital to closely monitor your investments For more data see the full report at bestinvest.co.uk/dogs