Investment Research Note — Calnex Solutions PLC (CLX)

Executive summary

Calnex designs high-performance test and measurement instrumentation for network synchronisation and network emulation, sold to telecoms operators, equipment vendors, hyperscalers, and government/defence customers globally. Revenue collapsed 41% in FY24 (£16.3m) as the telecoms capex cycle turned, but has since recovered to £21.9m in FY26 (+19% YoY) as diversification into digital infrastructure (49% of orders) and government/defence (21%) has offset weakness in the legacy telecoms end-market. The single most important valuation question is whether the operating leverage evident in FY23 (peak PBT of £7.2m on £27m revenue) can be re-attained as FY27–FY28 product launches (SNE for AI network validation, 1.6Tb/s sync testing, next-gen Sentry for data centres) commercialise.

Fair value estimate

Range: 55p – 80p per share, mid ~68p (implied market cap £48m – £70m, mid £60m)

• Methodology: Blend of forward P/E and EV/EBITDA on a normalised basis, cross-checked against peak-year profit.
• Key assumptions:
  • Bull-case FY28E PBT of £4–5m (management is explicitly guiding to a "step-change" in FY28 as new products commercialise; peak FY23 PBT was £7.2m)
  • Base-case FY28E PBT of £2.5–3.5m, applying 15–17x P/E to post-tax profit
  • Net cash £9–11m as at year-end / post-period
  • FY26 EBITDA £6.4m, Underlying EBITDA £1.76m (post-R&D amortisation) — I anchor on Underlying EBITDA since capitalised R&D (£6.3m in FY26) is real cost
• Latest disclosed market cap: £55.0m. At 62.3p, the current price sits inside my range but toward the lower end.
• Absolute upside vs mid: ~9% (from 62.3p to 68p). Range from –12% to +28%.

Sector context

• Sector: Telecommunications (ICB), but this is really a specialty electronic instruments/test-and-measurement business — comparable more to Spirent Communications, Viavi Solutions (VIAV), or Keysight (KEYS) than a telco.
• Quality/growth/leverage: Above-average balance-sheet quality (net cash, no debt) but below-average scale versus peers. Gross margin (76%) is peer-consistent for specialty T&M.
• Listed peers: Spirent Communications (recently acquired), Viavi Solutions (Nasdaq: VIAV) — Calnex is now selling into Viavi via a new O-RAN partnership. Keysight is a larger analogue.

Investment thesis

1. Genuine (though indirect) AI-receiver exposure via hyperscaler and defence networks. FY26 secured a "significant repeat Sentry order from a leading hyperscaler" for data-centre sync monitoring, plus post-period a 400G network emulation capability specifically for testing AI congestion/microbursts. Government/defence orders rose from 15% to 21% of orders. Digital infrastructure is 49% of orders 2026-05 FY26 Final Results.
2. High operating leverage into recovering revenue. Gross margin 76%, ~£11.1m fixed admin cost base, £4.6m R&D amortisation. FY23 shows the leverage: £27.4m revenue → £7.98m Underlying EBITDA (29% margin) versus FY26's 8%. A recovery of just £5m of revenue against a broadly flat cost base plausibly triples Underlying EBITDA 2026-05 FY26 Final Results, 2023-05 FY23 Final Results.
3. Fortress balance sheet with recurring, repeat-order franchise. Net cash £9.3m at 31 Mar 2026 (£11.2m at 22 May 2026), no debt, 79% of orders from repeat customers on 3-yr average, top-10 customer relationship averaging 13 years. Interim dividends maintained through the FY24 loss year 2026-05 FY26 Final Results.

Key risks

1. Customer concentration. One customer = 22% of FY26 revenue and 25% of orders 2026-05 FY26 Final Results. Loss of that hyperscaler relationship would be highly material.
2. Telecoms cycle is unpredictable and lumpy. FY24 profit warning showed how fast revenue can drop (–41%) when a small number of large telecoms projects are deferred 2024-05 FY24 Final Results, 2023-10 Trading Update. FY28 "step-change" is management-guided but unproven — timing risk on new products (1.6Tb/s, Sentry v2, SNE-X) is real.
3. China exposure and geopolitical risk. North Asia has been in "steady decrease since FY20 reflecting the ongoing US-China geopolitical tensions" and US restrictions on China trading remain a headwind 2026-05 FY26 Final Results. NAA product competition in China explicitly noted.

Operating leverage

Calnex has strong operating leverage characteristics: gross margin held at 76% in FY26 (75% in FY25, 73% in FY24, 75% in FY23) even as revenue swung between £16m and £27m — near-total pricing/margin discipline. The cost base is dominated by (a) £11.1m admin expenses (largely people, mostly UK Sterling) and (b) £4.6m R&D amortisation (5-year straight-line on ~£6.3m of annually-capitalised R&D). Both are effectively fixed. Underlying EBITDA margin: FY23 29% at £27.4m revenue, FY26 8% at £21.9m revenue. A return to £26–28m revenue at unchanged cost structure would plausibly deliver £5–7m Underlying EBITDA — 3–4x current levels on 20–30% revenue growth. Management is investing further in FY27 in R&D and sales/marketing headcount ahead of the FY28 commercialisation, so near-term operating leverage will be modestly diluted before it re-accelerates. Fixed R&D and central overhead won't scale with incremental revenue from AI-adjacent products 2026-05 FY26 Final Results.

Value-trap signals

• Customer concentration (22% from one customer) is the strongest red flag; not a value trap per se but a real fragility.
• North Asia is in structural decline with US-China tensions unlikely to abate.
• Telecoms end-market has been "subdued" for multiple years now — the "recovery" narrative has been recurring since FY24; peers report similar softness.
• Capitalised R&D of £6.3m in FY26 vs £4.6m amortised — cash R&D outflow exceeds P&L R&D expense, so underlying cash generation is weaker than statutory profit suggests (£1.6m cash outflow in FY26 despite £0.7m PAT).

Earnings vs. expectations

Reviewing the results across the period:

• FY23: Management guided "in line with market expectations" — delivered strong beat vs original expectations; revenue +25%, EBITDA +26%.
• FY24: Started year confident; issued Trading Update Oct 2023 warning FY24 revenue 20–30% below market expectations. Missed materially.
• FY25: Trading Update Apr 2025 said "in line with market expectations" — delivered.
• FY26: Trading Update Apr 2026 said "slightly ahead of market expectations" — delivered slightly ahead (revenue £21.9m vs prior guidance).

Pattern: One major miss (FY24, driven by exogenous telecoms downturn), otherwise consistent delivery in line to slightly ahead. Not a serial miss-er but not a serial beat-er either.

Conviction

Conviction: 3 (moderate).

What anchors it:

• Clean, transparent disclosure with detailed customer/geography/product-line breakdowns
• Multiple valuation approaches (P/E on normalised profit, EV/EBITDA, EV/Revenue) all triangulate on £45–70m market cap
• Balance sheet clarity — net cash is unambiguous

What limits it:

• FY28 profit acceleration is a management thesis, not yet in the numbers. If new products slip or land flat, current level is expensive
• Customer concentration (22% from one customer) creates binary risk that broadens the fair-value range
• Telecoms cycle timing is inherently hard to call — the H1/H2 phasing has been erratic

Driver scoring

• ai_beneficiary (55): Genuine picks-and-shovels exposure via hyperscaler Sentry orders, AI network validation with 400G SNE-X, and defence — but telecoms remains the core, and the AI orders are lumpy rather than a repeat revenue stream. Not dominant enough for HIGH.
• operating_leverage (72): Fixed R&D, 76% gross margin, spare organisational capacity — FY23 vs FY26 comparison shows the drop-through. Clear structural feature.
• earnings_surprise_trend (55): Slight recent beats, one significant miss (FY24). Marginally more beats than misses on balance.
• cyclicality (58): Telecoms capex cycle is meaningfully cyclical; FY24 showed this. Diversification into defence and hyperscalers should moderate future swings.
• moat (52): Specialised test IP, high repeat rates (79%), long customer relationships (13 years avg for top 10), but relatively small niche and Viavi/Keysight can compete.
• leverage (8): Net cash £9m, no debt, small leases. Fortress balance sheet.
• earnings_quality (55): Heavy R&D capitalisation weakens cash conversion (statutory £0.7m PAT vs £1.6m cash outflow in FY26). Otherwise clean.
• management_quality (65): Founder-led (Tommy Cook), maintained dividend through FY24 loss, navigated component shortages, sensible channel-partner transition from Spirent.
• growth_momentum (58): 19% growth in FY26 is strong; H1 FY26 was only +9%, so H2 accelerated. Management guides to further FY28 acceleration but FY27 is a "targeted investment" year — momentum is intact but modest.

Overall score: 500

Moderate fit. The AI-receiver exposure is real but indirect and lumpy (~55). Operating leverage is genuinely strong. Valuation is fair rather than cheap — you're paying for the FY28 recovery to happen. Downside protection is excellent (net cash, no debt, diversified base, 79% repeat orders). Not a top-band conviction pick given customer concentration and unproven FY28 step-change; better than average fit for this strategy's principles.