Portfolio Mix Shift

Where is the portfolio changing? Is growth improving or weakening the mix?

The Decision Question

Where is the portfolio changing, what is producing the change, and are the segments gaining share strengthening or weakening the expected result?

Default practice

Portfolio reporting usually starts with total premium growth, policy count and an overall loss ratio.

These measures establish the size and direction of the book, but they can hide a material change in composition.

Premium can increase while profitable segments contract, less adequate segments expand, or new business replaces attractive renewals.

Suggested upgrade

Show quarterly premium movement by segment and connect it to the resulting portfolio share. The bars separate renewal exposure change, rate movement, new business and lost business. The share line shows how movements are changing the weight of each segment in the portfolio.

How to Read the chart

Start with the segments. The largest movements sit on the left. Standard Motor is the dominant growth engine; Commercial Property provides the clearest counter-movement.

Read each segment from left to right. The five bars show when the movement accelerated or changed direction. Positive components build premium; lost business reduces it.

Compare the components. Distinguish growth from renewal exposure, achieved rate and new business. A large positive total driven mainly by new business creates a different portfolio question from renewal-led growth supported by rate.

Portfolio share. Standard Motor increases from 25% to 30%, while Commercial Property falls from 19% to 14%. Affluent Motor and SME Property remain broadly stable; Liability and Engineering edge down. 

Finish with the quality question. The chart identifies which segments are becoming more or less material. Compare those movements with rate adequacy, expected loss ratio, retention and volatility to determine whether the changing mix is favourable.

In this example, the rapid growth in Standard Motor requires review, while the continued loss of Commercial Property deserves investigation. 

Trade-offs and risks

The chart combines two units: premium movement on the left axis and portfolio share on the right.

The line should therefore be interpreted as context for the bars, rather than added to them. Consistent movement definitions are essential: isolate pure rate from changes in exposure, limits, sums insured and coverage; measure lost business against eligible renewals; and avoid allowing timing differences in written premium to create false shifts.

Segment results also need a credibility check. A large percentage movement in a small segment may be noise, while a modest movement in a large segment can materially alter the portfolio.

Written premium may be distorted by seasonality, large risks or multi-year policies. Where these effects matter, use earned premium, exposure or an annualised view and retain the same chart structure.

Decision Boundary

In the illustrative portfolio, the immediate questions are whether Standard Motor growth should continue at its current pace and why Commercial Property renewals are being lost. Rate adequacy, profitability and retention analysis should then determine the intervention required. The chart identifies where portfolio steering is needed; the supporting diagnostics explain whether to reprice, tighten, protect or continue growing.

This keeps the chart central and establishes an important boundary: it reveals the location and materiality of the shift, but does not independently prove whether the shift is attractive.