Jan 24, 2023, 1:00 PM ETInterview, Fireside Chat

The Ultimate Guide for Building a Two-Sided Marketplace | a16z's Jeff Jordan

Fragmented supply creates defensible moats: OpenTable succeeded where Fandango struggled because OpenTable aggregated 30,000–50,000 fragmented restaurants (mostly single-owner), whereas Fandango aggregated only six major movie chains; the latter granted suppliers significant bargaining power, allowing them to bypass the platform (e.g., booking directly via AMC.com).
Critical mass threshold: A tipping point for diner adoption occurs when approximately 10% of a market's supply is aggregated, shifting the user preference from "complete selection" to "convenience" over calling restaurants individually.
Two-sided strategy failure points: Founders often fail to acquire fragmented supply due to a weak value proposition; without robust supply, demand remains uninterested (the "Cold Start Problem").
Channel conflict risks: Marketplaces should generally avoid owning supply directly due to channel conflict with partners; for example, Instacart partners with grocers but would undermine this relationship if it opened its own warehouse grocery chain.
One-way door decisions: Transitioning to owning supply is a "one-way door" decision (Jeff Bezos concept) that is difficult to reverse, as seen with Netflix's successful but irreversible move into original content production.

Value of new customer acquisition: Marketplaces like OpenTable charged fees primarily because they provided restaurants with new customers seeking diverse dining experiences, rather than just digitizing existing repeat traffic which could be accessed via free tools.
Shift in discovery channels: TikTok is emerging as a primary search engine for discovery, with 45% of millennials using it instead of Google; Connie Chen notes this trend is already replacing Google use cases for restaurant discovery in China.
Capital efficiency over paid scaling: Investors increasingly avoid funding businesses reliant on heavy paid marketing to Google/Facebook due to eroding margins and lack of defensibility; Jeff Bezos' "bat signal" concept involves publishing specific investment theses to attract aligned founders rather than chasing trends.
Paid acquisition timing: Heavy spending on paid user acquisition is only justifiable when unit economics are proven and the business is comfortable with the cost of acquisition; otherwise, companies risk a "hamburger hill" scenario where capital is spent without a path to profitability.
Uber/Lyft capital inefficiency: 79% of the capital invested in Uber and Lyft is unlikely to return to investors, highlighting the critical need for capital efficiency and the dangers of fuel wars in markets with low barriers to entry (e.g., mattress-in-a-box companies).

Payment-to-execution duration as a key metric: The ideal marketplace features a long delay between payment and execution (e.g., Airbnb, Incredible Health) to generate working capital and improve capital efficiency; conversely, businesses like Uber and Instacart face pressure due to the short 10–20 minute window between payment and service delivery.
Cash flow positive milestones: Airbnb and Incredible Health became cash-flow positive before becoming operating income positive, allowing them to sustain growth with less external funding; Incredible Health could have theoretically taken an "A-to-IPO" path but raised capital to increase bank safety and value.
LTV/CAC volatility: Customer Acquisition Cost (CAC) is expected to rise over time due to competitive dynamics; a tight LTV to CAC ratio (e.g., 2:1 or 4:1) is a significant concern, whereas higher ratios offer more resilience.
Instacart unit economics turnaround: Instacart transformed from losing $20–$25 per order to profitability through continuous optimization, including dedicated grocery aisles, scan-and-go technology, and direct payment to grocers to eliminate shopper wait times.
Negative network effects: Scaling can degrade quality if supply cannot meet demand, leading to negative network effects (e.g., increased wait times and multi-stop deliveries in fast commerce) that drive churn.

Cohort retention metrics: Investors focus on the steepness of decline between first and tenth purchase; even with high user attrition (e.g., 75% decline for Instacart users after a year), revenue retention can remain strong if remaining users increase spend (3–4x), resulting in near 100% revenue retention.
Improving cohorts as a signal: If newer user cohorts show better retention or spend than older cohorts, it indicates a strengthening network effect where the platform becomes more valuable as it scales.
Messaging specificity: Successful marketplaces often start by targeting a specific, "outrageous" niche (e.g., eBay focusing on collectibles) before expanding to broader markets based on user behavior patterns (e.g., the accidental emergence of eBay Motors).
Airbnb's trust challenge: Airbnb's messaging had to reframe "strangers in strangers' homes" from a scary concept into an enticing community experience, focusing on "belonging" rather than traditional hospitality.

"No bad ideas, only bad timing": The investor maintains that failure often stems from poor timing rather than flawed concepts; Mike Moritz's transition from Webvan (failed) to Instacart (success) illustrates the importance of technological readiness (mobile adoption) in reviving similar business models.
Mental plasticity: Investors must avoid being jaded by past failures, continuously analyzing decisions based on the quality of the process rather than the outcome to maintain adaptability.
Blue-collar service gaps: Unbundling services (home repairs, rentals) has historically failed due to low frequency, high leakage, and the inability to build brand recall compared to core relationships (ride-sharing, home-sharing, dating).
Signal-based sourcing: The firm publishes specific content ("bad signals") to attract founders addressing specific theses (e.g., the blog post on the "on-demand economy" that led Perva to pitch Instacart) rather than waiting for founders to come to them.
Demand as the strategic priority: Maintaining healthy demand is the primary driver of marketplace equilibrium; suppliers will migrate to where demand exists, making a strong demand side the most critical factor for supplier retention.