Investors who have built a disciplined SIP portfolio often face a different challenge when they receive a large lump-sum amount. While long-term equity investing can help create substantial wealth, deploying a sizeable corpus at one go may expose investors to short-term market timing risks. Financial planners generally recommend a structured approach that balances growth opportunities with risk management, especially when the investment horizon extends over 15-20 years.One such query came from Sandhya, a viewer of The Money Show on ETNow, who is already investing through SIPs in a largecap fund, midcap fund, flexicap fund, and smallcap fund and now wants to invest an additional Rs 30 lakh for next 20 years. She wants to know the strategy to deploy such a large amount or use staggered investing and how she should ideally plan the allocation. Also Read | Multicap vs flexicap mutual funds: Which is better placed amid market volatility?She has invested in Nippon Largecap Fund around Rs 4,000 SIP. Motilal Oswal Midcap Fund Rs 2,000 per month SIP. HDFC Flexicap Rs 2,000 SIP. Quant Smallcap again Rs 2,000 of SIP. According to Nisreen Mamaji, MoneyWorks Financial Services, avoiding a direct lump-sum investment into equities is suggested.She said that Sandhya has actually selected an excellent portfolio as far as SIP goes, reasonably diversified. She is investing around Rs 4000 into largecaps, which according to Nisreen Mamaji is very good, and the rest of the Rs 6,000 is split over flexi, mid, and smallcaps. According to her, Sandhya has selected very good funds and should continue her SIPs. She noted that the existing allocation provides exposure across market capitalisations and advised continuing the SIPs as they are.Why a lump-sum investment may not be idealThe expert said that investing the entire Rs 30 lakh in one go could expose the investor to market-entry risk, especially if markets correct shortly after the investment. Instead, she recommended first parking the corpus in a liquid fund, money market fund, or arbitrage fund and then gradually transferring the money into equity funds through a Systematic Transfer Plan (STP)."The amount is quite large, and a staggered approach helps reduce the risk of investing at an unfavourable market level," she explained. The expert also suggested setting up an STP over the next 12 months.Investors can choose monthly, weekly, or even more frequent transfers depending on their comfort level. A monthly transfer of around Rs 2 lakh-Rs 2.5 lakh over a year can help average purchase costs and take advantage of any market corrections during the period.Suggested allocation for the Rs 30 lakh corpusFor the final equity portfolio, the expert recommends an allocation of Rs 8 lakh in a flexicap which is the core portfolio, it could be HDFC or HSBC. Midcap Index about Rs 7 lakh which could be the Nifty Midcap 150 Index, Rs 5 lakh in Bandhan or Nippon Fund which is the smallcap category. The expert further said that international exposure is recommended right now, but international funds are not taking money as of today, so one can wait for an opportunity where they are accepting international funds. The expert suggested Motilal Oswal Nasdaq 100 Fund but at this point they are not accepting money so just keep a look out for that and Rs 5 lakh in the HDFC Balanced Advantage Fund for stability. Also Read | Quant Mutual Fund bets on under-owned, under-researched, undervalued and neglected territory stocks for alpha generation The expert also said that the SIP and lumpsum combined would be invested for the next 20 years. SIP of Rs 10,000 a month would yield you about Rs 1 crore at 12% compounded annualised growth rate and your lumpsum of 30 lakhs would yield you about 2.9 to 3.5 crores depending on whether your CAGR is between 10% to 14%.Lastly, the expert mentioned that the total expected corpus is between Rs 4 crore to Rs 4.5 crore. So, the investor has already got a very good equity exposure, so she does not want to add too many new funds. Focus on increasing your allocation to quality and to the existing funds rather than expanding too much. So also, be sure that you do reviews regularly to make sure that your funds are performing and you are on track. For investors with a long investment horizon, a large lump-sum corpus can be a powerful wealth-creation tool. However, experts recommend deploying such amounts gradually through STPs rather than investing everything at once. Combining diversified equity exposure with some stability-oriented investments and periodic reviews can help investors maximise long-term returns while managing market volatility.(Disclaimer: Recommendations, suggestions, views and opinions given by the experts are their own. These do not represent the views of The Economic Times)If you have any mutual fund queries, message on ET Mutual Funds on Facebook/Twitter. We will get it answered by our panel of experts. Do share your questions on ETMFqueries@timesinternet.in alongwith your age, risk profile, and Twitter handle.