Source: Lipper/Moneyfacts Note: The table above is ordered by the best performance 1 April 2021 over the past 12 months. Funds may be available on other platforms not listed, through a stockbroking service or financial adviser. This month, there have been two new entrants into the best performing investment ISAs over the past 12 months. Guiness Sustinable Energy B Account and MFM TechInvest have both moved up the chart to second and third places. The best performing Investment ISA in April 2021 for the sixth month in a row was from Baillie Gifford American A Account. A £1,000 investment made into this fund 12-months would now be worth £2,029.91.