A value fund has lagged its benchmark by 4% a year for three years, but its downside capture is 70% and upside capture 85%. A platform wants to drop it. When would it be expected to win, and would you keep it?

The fund is built to lag strong markets and win in falls, and one bad year would erase three years of lag. A 4-point lag at 85% capture implies the market rose about 26.7% a year. A single year in which the market falls about 25% would put the fund back level over the four years, because it would lose only 17.6%. Keep it if the process is unchanged and the capture comes from enough down months, and label it as the defensive holding it is.

They describe how much of the market's move the fund takes in each direction. A cautious driver on a highway reaches the next town later than the car ahead in clear weather and passes it in fog. Upside captureThe fund return in months the market rose, divided by the market return in those months. Below 100% means the fund keeps less than the full rise. of 85% means the fund keeps 85% of every rise; downside capture of 70% means it takes 70% of every fall. Upside above downside is what a good defensive fund looks like. The lag is not a malfunction. It is the fund doing what it says in exactly the market it does least well in.

Work backwards from the lag. Missing 15% of the market's gain cost 4 points, so the market rose about 4 divided by 0.15, about 26.7% a year, three years in a row. That is an exceptional run, and it is precisely the environment in which a 70/85 fund trails. Now ask what brings it level. Compounded over three years, the market grew 2.032 times and the fund 1.846 times. One year in which the market falls about 25% closes the gap: the fund loses 17.6% and the four-year totals meet.

Three things, each of which could turn the answer. First, whether the 70% downside capture rests on real falls or on a handful of mild down months; seven years of monthly data should contain at least one sharp fall, and you want to see the fund held up in it. Second, whether the lag matches the value style: if a value index also trailed by about the same amount, the manager is being paid for exposure the platform chose, not failing at it. Third, whether anything changed, manager, team, fund size or a drift into expensive stocks. If the process is intact, dropping the fund after three strong years sells the insurance just after paying three years of premiums.

Close with a view and a condition. Keep it, but move it from the core list into a clearly labelled defensive slot, so investors who buy it know it will trail in good years. Set the test in advance: if the next real market fall arrives and downside capture comes in above 90%, the thesis has failed and the fund goes. The platform's harder problem is behavioural. Investors who bought three years ago and leave now lock in the lag and never collect the protection.