S&P Global Composite PMI

What is S&P Global UK Composite PMI?

The S&P Global UK Composite PMI, or Purchasing Managers' Index, measures month to month change in UK private sector output. Its headline is the Composite Output Index, a seasonally adjusted figure that removes normal seasonal swings. The survey covers around 650 manufacturers and around 650 service firms.

The service panel spans consumer, transport, information, communication, finance, insurance, real estate and business services. Panels are stratified by detailed sector and workforce size using GDP shares. The index is not GDP and not absolute output.

It excludes construction, retail, agriculture and the public sector. It tracks manufacturing plus services only.

When is it released and what happens each release?

Responses are collected in the second half of each month. They ask about change from the previous month. A flash estimate appears near day 23 from around 80% to 90% of responses.

The final manufacturing release follows at the start of the following month. The final services release carries the final Composite Output Index a few days later. All releases stay embargoed until 09:30 London time, with exact dates set by the publisher calendar.

The flash prints composite, services activity, manufacturing output and manufacturing PMI together. The services final adds sub indices for new business, employment, backlogs, prices and expectations. Survey data are never revised after publication. Only seasonal factors change later, and finals replace flash estimates.

What moves S&P Global UK Composite PMI?

Only 2 input indices drive the composite, with services carrying the larger GDP weight.

• Manufacturing Output Index: captures monthly change in the volume of manufacturing output from the output question.
• Services Business Activity Index: captures monthly change in the volume of services business activity from the activity question.

The composite rises when its inputs rise and falls when they fall. A reading above 50.0 means overall expansion from the prior month.

A reading below 50.0 means overall contraction. Distance from 50.0 shows the pace of change. Markets read the level against 50.0 and the direction of change.

How is S&P Global UK Composite PMI calculated?

1. Diffusion index: for each question the index equals higher responses plus half of unchanged responses, or D = H + 0.5 × U. Scores run from 0 to 100. For illustration, 30% higher with 50% unchanged gives D = 30 + 0.5 × 50 = 55.0.

1. Input indices: the Manufacturing Output Index is the diffusion index for factory output volume. The Services Business Activity Index is its direct equivalent for services activity.

1. Weighted average: the composite is a weighted average of the 2, with w_m + w_s = 1 and weights from official GDP shares. For illustration, 0.2 × 45.0 plus 0.8 × 52.0 equals 50.6, so strong services offset weak manufacturing.

1. Seasonal adjustment: the indices are seasonally adjusted. The published headline is the adjusted composite.

Key point: the composite is not comparable with the headline Manufacturing PMI. The composite blends 2 indices, while the manufacturing headline blends 5 variables. Only manufacturing output feeds the composite, not the 5 component headline.