Most weeks in this series we pull the individual five-digit SIC code attached to each of the 650 UK companies Archive Partners tracks and rank them by frequency or by turnover. That table has looked the same for a while now: “other business support service activities not elsewhere classified” (82990) is the single most common code, carried by 30 companies, and “activities of other holding companies” (64209) carries the most combined turnover, £1.62 billion across 28 firms. This week we asked a different question: what happens if you stop counting individual five-digit codes and group them into the broader SIC sections they belong to — construction, manufacturing, wholesale and retail trade, financial services, and so on? The leaderboard doesn’t just shift. It flips.
At the section level, wholesale and retail trade is the largest single grouping in our tracked population by a wide margin — 126 companies, 19% of the full 650, with £3.93 billion in combined turnover, more than any other sector. Yet no individual five-digit code inside that section comes anywhere near the top of a single-code table. The largest is 47910 (retail sale via mail order or internet), held by 9 companies; 47110 (non-specialised retail, mostly food) accounts for 7 companies but £377.4 million in turnover; 45200 (vehicle maintenance and repair) has 6; 47220, 46900 and 46130 each carry 4–6 companies apiece. None of these individually beats 82990’s 30 companies or 64209’s £1.62 billion. Trade only becomes visible as the dominant sector once you stop looking at any single code and add the whole family together.
Manufacturing and construction tell the same story from slightly different angles. Manufacturing spans 112 companies and £2.44 billion in turnover, spread across dozens of distinct codes covering everything from food processing to metal fabrication — no single manufacturing code appears near this series’ usual top-ten lists. Construction, covered before as a recognisable “sector story” (77 combined instances across its four core codes back in early August), totals 99 companies and £2.42 billion, but even its best-known code (41202, residential construction) carries only 22 companies on its own, well short of 82990’s 30.
Financial and insurance activities sit at the opposite extreme. The section totals £2.07 billion across 43 companies — smaller as a whole sector than trade, manufacturing or construction. Almost all of that weight comes from a single code: 64209 alone accounts for £1.62 billion of the section’s £2.07 billion, so one narrow catch-all label does most of the work for an entire SIC section. Energy supply is the extreme version of the same pattern: just 4 companies carry an energy-supply code, for a combined £932.9 million, and £926.1 million of that — essentially the entire sector — belongs to one company, Pozitive Energy Ltd. A four-member sector can still crack a top-ten-by-turnover list if one of the four is large enough.
The pattern underneath both halves of this comparison is the same: some sectors (trade, manufacturing, construction) are large because they are broad — dozens of adjacent five-digit codes, no single one dominant, that only show their true size once summed. Others (financial services, energy) look smaller in aggregate but are carried almost entirely by one or two codes, or even one company, so their apparent size is fragile in a way trade’s isn’t. A single-code leaderboard systematically favours the second pattern, because a catch-all label like 82990 concentrates many similar-but-distinct businesses under one code where a specialised retailer or manufacturer gets split across several. It’s not that 82990 and 64209 are unimportant — they’re the most efficient labels for finding a lot of similar companies at once — but “most common code” and “largest sector” are different questions, and this week’s data shows they can point in opposite directions. For sizing an actual market rather than spotting an outlier, the section-level view is the one worth trusting; the single-code table is better suited to finding the next Pozitive Energy.
125 of the 650 companies carry more than one SIC code, so the section counts above slightly overstate footprint by counting a company in every section it touches — but the effect is marginal and doesn’t change which sections lead either table.