SDI Group plc (SDI) — Investment Research Note

Executive summary

SDI is an AIM-listed "buy and build" group operating 17 subsidiaries that design and manufacture specialist lab equipment, industrial/scientific sensors and scientific products, with FY26 revenue of £74.5m across three divisions. Across the period covered, the group has delivered a CAGR of 24.1% in revenue and 36.0% in adjusted operating profit since 2015, with FY26 showing a return to healthier organic growth (5.5%, accelerating to 6.7% in H2 constant currency) alongside two earnings-enhancing acquisitions (Severn Thermal Solutions, PRP Optoelectronics). The single most important point for valuation today is that the shares now trade on roughly 11x FY27 broker-consensus adjusted PBT (£11.2m) with £24m of net debt post-acquisitions — a reasonable entry point for a proven serial acquirer, but one whose "AI beneficiary" credentials are indirect at best.

Fair value estimate

• Fair value range: 95p – 115p per share (implied market cap £99m – £120m)
• Methodology: cross-check of (a) forward P/E on FY27 broker consensus adjusted EPS of ~7.9p (7.7% tax-adjusted PBT of £11.2m on 107m diluted shares) at 12–14.5x = 95p–115p; and (b) EV/EBIT on FY27 consensus adjusted operating profit of £13.1m at 9–11.5x, deducting £24m net debt = ~97p–118p per share.
• Key assumptions: FY27 delivered in line with consensus; net debt reduced modestly through cash generation; multiple appropriate for a mid-teens-growth acquisitive industrial with moderate leverage on the UK small-cap market.
• Compared to current market cap of £95.2m, mid-point fair value of £110m implies ~15% absolute upside.

Sector context

Confirmed as Industrials / Industrial Goods and Services (ICB). SDI's quality (mid-teens adjusted operating margins, 66% material gross margin, R&D-supported niches) is broadly in line with sector norms; growth is a touch above the sector average but leverage (net debt ~1.5x EBITDA post-acquisitions) is moderately higher than the sector median. Listed UK peers with a similar buy-and-build model in scientific/industrial niches include Judges Scientific, Halma (larger, higher quality/multiple), discoverIE, and Diploma.

Investment thesis

• Proven serial acquirer with rebuilt firepower. Renewed £25m HSBC RCF plus £15m accordion in November 2025 means the pipeline is fully funded; two accretive deals (Severn £4.8m, PRP £9.3m) landed in FY26 already contributing profitably to H2 2026-07 final results. Track record CAGR of 36% adj. operating profit since 2015 2026-07 final results.
• Emerging aerospace/defence and semi-adjacent exposure improves mix. PRP supplies mission-critical microLEDs to Eurofighter Typhoon, F-16 and F-22 platforms; Chell dominates F1 (10 of 11 teams post-Cadillac) and won Tempest work; Severn is now selling vacuum furnaces to the UK Atomic Energy Authority and blue-chip nuclear/aerospace/semi customers 2026-02 PRP acquisition; 2026-07 final results.
• Valuation is undemanding for the buy-and-build compounding model. At 91p the shares sit on ~11.3x FY27 consensus adjusted PBT and ~12.7x FY27 adjusted EPS versus historical highs of 20–25x; recent H2 organic acceleration (7.6% absolute) and £27m drawn against a £34m facility suggest the group can compound further without near-term dilution 2026-05 trading update; 2026-07 final results.

Key risks

• Balance-sheet leverage now materially higher. Net debt jumped from £13.8m to £24.0m in FY26 to fund acquisitions; further large deals may require equity or push covenants closer to stress in a severe downside 2026-07 final results, going-concern note.
• Deal-driven earnings introduce integration and impairment risk. SDI wrote down £3.5m of Monmouth/Uniform goodwill and intangibles in FY23, and Monmouth was again impaired in the parent by £1.1m in FY26; adjusted-to-reported OP gap of £3.4m in FY26 (mainly acquired intangible amortisation) means reported EPS trails adjusted by ~35% 2023-08 final results; 2026-07 final results.
• "AI beneficiary" credentials are thin. Only a modest slice of revenue (SVS sputter equipment, Severn furnaces to semi customers, PRP microLEDs) is directly geared to the AI capex cycle; the majority of the portfolio serves lab, water, F&B, aerospace/defence and general industrial customers with limited pricing power over AI demand (not disclosed but inferred).

Operating leverage

SDI's cost base is a mix of variable materials (34% of revenue) and semi-fixed staff (£27.9m or 37% of revenue) plus fixed central costs (£3.3m). Gross margin on materials of 66.0% (FY25: 64.9%) and reported adjusted operating margin of 15.5% imply that incremental revenue at existing sites earns closer to the material gross margin than the group operating margin — because much of the staff base and all central costs are fixed in the short run. The FY26 divisional data illustrates this: Sensors delivered 22.9% revenue growth for 16.9% adj OP growth (mixed by PRP dilution), Lab Equipment 12.4% revenue for 29.7% adj OP growth, and Products 5.6% revenue for 23.2% adj OP growth. A 10–20% revenue surprise across the group would plausibly add 25–50% to adjusted operating profit at current scale, i.e. meaningful but not "multiples of profit" — this is a classic industrial with modest, not extreme, operating leverage 2026-07 final results.

Value-trap signals

None identified. Revenue is growing, organic growth is re-accelerating in H2 FY26, the audit is unqualified, cash generation is real (£10.2m cash from operations), the balance sheet is manageable (net debt/EBITDA ~1.5x), and there is no obvious customer concentration (no customer >10% of revenue). The main watch item is the multi-year pattern of adjusted-vs-reported earnings gaps driven by amortisation of acquired intangibles, which is inherent to a buy-and-build model.

Earnings vs. expectations

• FY22 (Jul 2022): Guided upward twice pre-results, then delivered adj PBT of £11.8m vs prior consensus £9.65m — material beat.
• FY23 (Aug 2023): Adj PBT £11.8m in line with revised expectations, but H1 profit warning in Dec 2022 flagged destocking — mixed / met after guide-down.
• FY24 (Jul 2024): Adj PBT £8.0m broadly in line, but management cut FY25 guidance versus prior consensus at these results — met FY24, guided down FY25.
• FY25 (Jul 2025): Adj PBT £8.5m in line with market expectations of £8.4m — met.
• FY26 (Jul 2026): Adj PBT £9.9m vs market of £9.8m — met (slight beat).

Pattern: after strong beats in the exceptional COVID-camera years, the group has settled into a "guide and meet" cadence with one downgrade (FY24 → FY25 guidance cut) but no repeated misses. This is a "reliable in-line deliverer" rather than a chronic beater or misser.

Conviction

Conviction: 3 (moderate).

• Anchors: clean audit, consistent disclosure, established methodology of forward multiples plus EV/EBIT converging on a similar range, and multiple external broker forecasts (Cavendish, Stifel, Progressive) triangulating consensus.
• Limits: valuation depends on whether the market re-rates a serial acquirer whose historical multiple was much higher, and on the group's ability to keep landing accretive deals; the adjusted-vs-reported gap and £36.5m of goodwill mean impairment risk is non-trivial.