What is the difference between AIM and the Main Market?

AIM (Alternative Investment Market) is the London Stock Exchange's growth market designed for smaller and younger companies. The Main Market is the listing venue for larger, established companies; since July 2024 most commercial companies list in a single category, Equity Shares (Commercial Companies) or ESCC, which replaced the old Premium and Standard segments. Key differences: AIM has no minimum market capitalisation, no minimum trading history and no minimum free float, and requires a Nominated Adviser (Nomad) rather than an FCA-approved sponsor. An ESCC listing requires a sponsor, a minimum market capitalisation of £30M, at least 10% free float, an FCA-approved prospectus and compliance with the UK Listing Rules. AIM is more flexible and less costly, making it the typical first listing venue for UK startups.

How long does it take to prepare for an IPO?

A typical AIM IPO takes 12-18 months of preparation before the listing date. A Main Market listing takes 18-24 months. The timeline includes: selecting advisers (months 1-3), financial and legal due diligence (months 3-8), preparing the admission document or prospectus (months 6-12), HMRC and regulatory filings (months 10-14), investor roadshow and bookbuilding (months 12-16), and admission and first trading (month 16-18 for AIM). Companies that have maintained clean financials, robust governance, and structured intangible asset records can compress this timeline by 3-6 months.

What are the costs of an AIM IPO?

Total costs for an AIM IPO typically range from £500K to £1.5M, depending on the size and complexity of the transaction. This includes Nomad fees (£100K-£250K), broker fees (3-5% of funds raised), legal fees (£150K-£300K), accounting and reporting accountant fees (£100K-£200K), financial PR (£50K-£100K), and LSE admission fees. Ongoing annual costs of maintaining an AIM listing run to £200K-£400K including Nomad retainer, broker retainer, audit, registrar, and regulatory compliance. Main Market listings cost 2-3x more in both IPO and ongoing fees.

What role do intangible assets play in an IPO prospectus?

Intangible assets are central to a technology company's IPO narrative. The admission document or prospectus must describe the company's key assets, competitive advantages, and risk factors — all of which relate to intangible assets. Specifically, the prospectus should articulate: proprietary technology and intellectual property (patents, trade secrets, software), customer relationships and contract structures (recurring revenue evidence), brand equity and market position, assembled workforce and key person dependencies, and data assets and network effects. Most of this value does not appear on the balance sheet: intangibles are recognised separately from goodwill under IFRS 3 only when acquired in a business combination, and internally generated intangibles are recognised under IAS 38 only where strict criteria are met (for development costs, from the date those criteria are met). The narrative sections carry the rest, so companies that have tracked their intangible assets before the IPO can evidence that narrative rather than assert it.

What financial history is required for an IPO?

For AIM: there is no formal minimum trading history requirement, but the admission document must include historical financial information covering the last three years (or the period since incorporation, if shorter), and Nomads expect audited accounts and a credible business plan. For an ESCC listing on the Main Market: the three-year revenue track record test was removed in July 2024, but the prospectus still normally carries three years of audited historical financial information. Main Market companies must prepare their accounts under UK-adopted IFRS. Since 5 August 2026, UK-incorporated AIM companies may report under either IFRS or UK GAAP (FRS 102), so an AIM float no longer forces an IFRS conversion. A Main Market listing, or a later move up from AIM, still does, and IFRS 1 applies that conversion retrospectively, without hindsight. Revenue recognition policies, particularly for SaaS and recurring revenue models, receive close scrutiny during the reporting accountant's review.

What governance structures does a listed company need?

AIM companies must adopt a recognised corporate governance code and explain how they comply with it; most choose the QCA Corporate Governance Code. ESCC companies on the Main Market report against the UK Corporate Governance Code on a comply-or-explain basis. Both expect: a board with a balance of executive and independent non-executive directors, an audit committee (at least 2 independent NEDs), a remuneration committee, defined roles for Chair and CEO (should be different people), share dealing policies for directors and staff, and regular board evaluations. Companies should also establish a nomination committee and consider an ESG/sustainability committee. Strong governance is itself an intangible asset — it signals organizational capital maturity and reduces investor risk perception.

How does IPO readiness affect company valuation?

There is no reliable published figure for an 'IPO readiness premium', but the mechanics are clear. Preparation reduces execution risk (advisers, governance and reporting are already in place), improves financial transparency (audited IFRS accounts with clean opinions), and gives investors evidence for the intangible assets the valuation depends on. The same preparation helps if you ultimately choose a trade sale, because buyers price the same risks.

What is a Nominated Adviser (Nomad) and why is it required?

A Nominated Adviser (Nomad) is an advisory firm approved by the London Stock Exchange to guide and supervise companies listed on AIM. Every AIM company must retain a Nomad at all times — losing your Nomad results in suspension from trading. The Nomad's responsibilities include: assessing the company's suitability for AIM admission, guiding the company through the IPO process, ensuring the admission document is fair, balanced and not misleading, advising on ongoing regulatory obligations, and confirming that the company has appropriate systems and controls. Nomads act as gatekeepers for AIM quality and are personally liable for their assessment of a company's suitability.

IPO Preparation

How Do Startups Go Public? AIM, the Main Market and Intangible Assets

Taking a startup public is the ultimate liquidity event — but it demands years of preparation, significant investment, and a clear narrative about what makes your company valuable. For UK startups, the London Stock Exchange offers two primary venues: AIM for growth companies and the Main Market for larger, established businesses. This guide covers the full IPO preparation journey, with particular focus on the intangible asset documentation that underpins your prospectus and drives your listing valuation.

AIM vs Main Market: Choosing Your Listing Venue

The choice between AIM and the Main Market depends on your company’s size, maturity, and strategic objectives. Most UK startups that pursue an IPO list on AIM first, with the option to transfer to the Main Market as they grow.

Listing Venue Comparison

Requirement	AIM	Main Market (ESCC)
Minimum market capitalisation	None	£30M
Minimum trading history	None (Nomad discretion)	No revenue track record test since July 2024; prospectus normally carries 3 years of audited financial information
Minimum free float	None (10%+ typical)	10%
Accounting framework	UK-adopted IFRS or FRS 102 (FRS 102 permitted since August 2026)	UK-adopted IFRS
Regulatory framework	AIM Rules + Nomad	UK Listing Rules + sponsor + FCA
Governance code	QCA Code	UK Corporate Governance Code
Admission document	AIM Admission Document	FCA-approved Prospectus
Typical IPO cost	£500K–£1.5M	£1.5M–£5M+
Annual listing cost	£200K–£400K	£500K–£1M+
Typical company stage	Series B+ / Growth	Late-stage / Profitable

Key Takeaway: AIM is designed for growth companies that are not yet ready for the Main Market. It offers a lighter regulatory framework, lower costs, and no minimum size requirements — making it accessible to venture-backed startups with strong growth trajectories and compelling intangible asset portfolios.

---

The IPO Timeline: 18 Months to Listing

Months 1–3: IPO Readiness Assessment

Evaluate your readiness across five dimensions: financial (audited accounts, clean opinions), governance (board composition, committees), legal (IP ownership, contracts, litigation), operational (systems, controls, reporting), and intangible assets (identified, categorised, valued). Address gaps before engaging external advisers.

Months 3–6: Appoint Advisers

Select your Nomad (for AIM) or Sponsor (for Main Market), broker, reporting accountant, legal advisers, and financial PR firm. Run a competitive process — adviser chemistry and sector expertise matter as much as fees.

Months 6–10: Due Diligence and Documentation

The reporting accountant conducts financial due diligence. Legal advisers review all contracts, IP, and litigation. Prepare the long-form report, working capital statement, and pro forma financials. Begin drafting the admission document.

Months 10–14: Admission Document and Regulatory

Finalise the admission document (AIM) or prospectus (Main Market). For Main Market, submit to the FCA for review and approval. For AIM, the Nomad certifies the document. Complete all regulatory filings and pre-marketing preparations.

Months 14–16: Investor Roadshow and Bookbuilding

Present to institutional investors over 2–3 weeks. The equity story must articulate your competitive advantages — particularly intangible assets — and your path to sustained growth. Build the order book and agree the offer price with your broker.

Months 16–18: Pricing, Admission, and First Trading

Finalise pricing, allocate shares, complete admission formalities with the LSE, and begin trading. The first 30 days of trading are critical for establishing liquidity and market confidence.

---

Intangible Assets in the IPO Process

For technology companies, intangible assets are the primary value driver — yet they receive inconsistent treatment in most IPO processes. Companies that proactively document and value their intangible asset portfolio achieve measurably better outcomes.

Enterprise Value from Intangibles > 90%

Years of audited financial information in a typical admission document 3

Intangible Assets Required in the Prospectus

Intangible Asset Category	Prospectus Section	What Investors Want to See
Technology & IP	Business Description, Risk Factors	Patent portfolio, trade secrets, defensibility assessment, R&D pipeline
Customer Relationships	Business Description, Financial Review	Top customer concentration, contract terms, retention rates, NDR
Brand Equity	Business Description, Market Overview	Brand awareness, market position, organic acquisition metrics
Assembled Workforce	Directors & Employees, Risk Factors	Key person dependencies, retention plans, equity incentive schemes
Data Assets	Business Description, Competitive Advantages	Proprietary datasets, network effects, data governance, GDPR compliance
Organizational Capital	Governance, Internal Controls	Processes, systems, scalability evidence, compliance frameworks

Example: When a SaaS company lists on AIM, its admission document must explain why the business is valuable beyond its current revenue. The intangible asset narrative — proprietary technology, customer lock-in, data moats, and brand — is what justifies the revenue multiple investors are being asked to pay. Companies that present this narrative with structured, evidenced intangible asset data achieve higher listing valuations.

---

Before You Float: Four Areas to Get in Order

Use these four areas to test where your company stands. They reflect what your Nomad or sponsor, the reporting accountant and your lawyers will review; the intangible asset area is good practice rather than a rule. For the full list, with the intangibles and valuation workstreams, a timeline and owners, see our IPO readiness checklist.

Financial Readiness

Audited accounts under the right framework (IFRS for the Main Market; IFRS or FRS 102 for AIM)
Clean audit opinion (no qualifications)
Working capital sufficient for 12 months post-IPO
Robust financial controls and reporting
Tax affairs current and compliant

Governance Readiness

Board includes independent NEDs
Audit and remuneration committees established
QCA or UK Corporate Governance Code adopted
Share dealing code in place
Company secretary appointed

Legal Readiness

All IP properly assigned to the company
Key contracts reviewed and documented
No material litigation or contingencies
Articles of association fit for a listed company
Employee share schemes compliant and documented

Intangible Asset Readiness

Intangible assets identified and categorised
Valuation methodology documented
Key person dependencies mitigated
Customer concentration risk addressed
Data governance and GDPR compliance evidenced

Note: The intangible asset readiness section is not a formal regulatory requirement, but companies that address it proactively produce stronger admission documents and face fewer questions from institutional investors during the roadshow. It is increasingly expected by sophisticated investors.

---

Start Your IPO Preparation Today

IPO preparation begins years before the listing date. Opagio Intangibles helps you build the structured intangible asset documentation that underpins your prospectus narrative. Start by understanding what you have built: map your technology capital, customer relationships, and brand equity — then track how they grow as you approach listing readiness.

For the accounting side, our IAS 38 vs FRS 102 Section 18 comparison works through an FRS 102 company moving to IFRS before an AIM listing, and the public listing playbook covers the intangible assets investors look for. Weighing other routes to market? Compare a direct listing with an IPO or a SPAC merger with an IPO.

Whether you are 6 months or 6 years from a potential IPO, measuring your intangible assets today creates the evidence trail that will support your valuation and strengthen your pitch to investors.

See Opagio Intangibles in action Take the Free Intangibles Assessment