A client wants to put Rs 5 lakh of his Rs 20 lakh portfolio into a new manufacturing theme fund. His flexi cap fund already has 34% in the same sectors, and the switch would lift that to about 50%. Should the NFO money go in?

No, not at Rs 5 lakh: the switch takes his manufacturing exposure from 34% to 49.5%, adding concentration, not diversification. A 30% fall in those sectors would cost him Rs 2.97 lakh instead of Rs 2.04 lakh. He already holds more than the market's 28%. If he insists on the theme, a switch of about Rs 1.9 lakh keeps the cluster at an illustrative 40% ceiling, and waiting for a track record costs little.

Not necessarily. A family that owns two cars and buys a third, also a hatchback, has more cars but no more ways to travel. A theme fund holds a narrow slice of the market, and the question is whether that slice is something the client does not already own. Here it is not. The flexi cap fund already puts 34% of his money into the same manufacturing sectors, more than the roughly 28% the broad market carries. The new fund offer is a decision about how much more of the same he wants, dressed as a new product. A new fund offerThe initial subscription period of a new scheme, when units are sold at a fixed price, usually Rs 10, before the fund starts trading at its own NAV. at Rs 10 a unit is not cheaper than an existing fund either: the price is just the starting point of a new NAV.

Weight each fund by the money in it. Rs 15 lakh left in the flexi cap at 34% is Rs 5.1 lakh; Rs 5 lakh in the theme fund at 96% is Rs 4.8 lakh. Rs 9.9 lakh of his Rs 20 lakh, 49.5%, would sit in one cluster of related sectors. These sectors also move together: a slowdown in capital spending, a rise in commodity prices or a change in import duties hits capital goods, components and electricals at the same time. So the exposure is more concentrated than the sector labels suggest.

Run one stress. Suppose manufacturing stocks fall 30% while the rest of his holdings are flat. Today that costs him 10.2% of the portfolio, Rs 2.04 lakh; after the switch it costs 14.85%, Rs 2.97 lakh. The extra Rs 0.93 lakh of loss is what the switch adds in a bad year for the theme, and themes do have bad years, often soon after the moment they are easiest to sell, when recent returns are strongest.

Three things the campaign will not mention. First, the switch is a sale: units redeemed from the flexi cap realise capital gains, and any units held under the exit load period pay that too, so the theme fund must be good enough to cover a known cost on day one. Second, there is no record to judge: a new fund has no portfolio, no history of how the manager handles a sector fall and no expense ratio at scale. Third, stock overlap: many of the large manufacturing names the theme fund is likely to own may already sit in the flexi cap's top holdings, which the factsheets will show once the new fund publishes its first portfolio.

Close with a clear view. The NFO money should not go in at Rs 5 lakh. If Vivek wants the theme because he believes in a long manufacturing cycle, a switch of about Rs 1.9 lakh keeps the cluster at 40%, still a deliberate tilt above the market. The better option is often to wait six to twelve months, see the fund's actual portfolio and how it behaves, and use fresh money rather than a taxable switch. The limit of the analysis: the 40% ceiling is a judgement, not a rule, and a client with a long horizon and a strong view can rationally hold more, provided he knows that is what he is doing.