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 (including the Premium and Standard segments) is the primary listing venue for larger, established companies. Key differences: AIM has no minimum market capitalisation requirement, no minimum trading history, no minimum free float percentage, and requires a Nominated Adviser (Nomad) rather than an FCA-approved sponsor. The Main Market requires a minimum 3-year trading history, at least 25% free float, a minimum market capitalisation (typically £30M+), 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. Under IFRS 3 and IAS 38, identifiable intangible assets must be separately valued in the IPO balance sheet. Companies that have tracked their intangible asset portfolio pre-IPO produce stronger prospectus narratives and achieve higher IPO valuations.

What financial history is required for an IPO?

For AIM: there is no formal minimum trading history requirement, but Nomads typically require at least 12-18 months of audited financials and a credible business plan. For the Main Market Premium Segment: a minimum 3-year audited financial history is required, with the most recent audit no more than 6 months old at the date of the prospectus. All financials must be prepared under IFRS (International Financial Reporting Standards) for Main Market listings. AIM companies can use UK GAAP (FRS 102) but many choose IFRS for international investor credibility. 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 the QCA Corporate Governance Code (or explain non-compliance). Main Market Premium companies must comply with the UK Corporate Governance Code. Both require: 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 organisational capital maturity and reduces investor risk perception.

How does IPO readiness affect company valuation?

IPO-ready companies consistently achieve higher valuations than comparable private companies — the 'IPO readiness premium' ranges from 15-30%. This premium reflects reduced execution risk (advisers, governance, and reporting are already in place), better financial transparency (audited IFRS accounts with clean opinions), stronger intangible asset documentation (identified, measured, and defensible), professional governance structures, and established investor relations capability. The premium is available even to companies that ultimately choose trade sale over IPO, because the same preparation that makes a company IPO-ready also makes it a more attractive acquisition target.

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

Startup IPO Guide: AIM vs Main Market, Preparation & Intangible Asset Requirements

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 (Premium)
Minimum market capitalisation	None	£30M+ (practical)
Minimum trading history	None (Nomad discretion)	3 years audited
Minimum free float	None (10%+ typical)	25%
Regulatory framework	AIM Rules + Nomad	UK Listing Rules + 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.

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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.

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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%

IPO Readiness Premium 15–30%

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
Organisational 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.

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IPO Readiness Checklist

Use this checklist to assess your company’s readiness for a public listing. Each item maps to a specific requirement in the AIM Rules or UK Listing Rules.

Financial Readiness

Audited financial statements (IFRS or FRS 102)
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.

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Start Your IPO Preparation Today

IPO preparation begins years before the listing date. The Opagio Intangible Asset Valuator 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.

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.

Try the Intangible Asset Valuator Take the Free Intangibles Assessment