A lump sum option is suitable for a MF that has a good credit score i.e. AAA or AA+, has performed over and above the benchmark returns compared to the mutual funds in the same category.The MF has performed consistently based on historical returns and has performed relatively well even when the market is facing a downward trend.This shows how well the underlying assets have performed when other funds were facing negative fluctuations due to market trend. You can also choose to invest in a debt MF for lump sum investment.However,it is always advisable to consider SIP or a systematic transfer plan STP.