Two numbers bookended 2026 for anyone tracking Southeast Asian ecommerce, and both were reported as fact: $157.6 billion and $226 billion. In April, Momentum Works reported that the region's platform ecommerce gross merchandise value reached $157.6 billion in 2025, up 22.8 percent. In October, Google, Temasek and Bain projected ecommerce GMV of $226 billion for 2026 in the eleventh e-Conomy SEA report, an 18 percent rise from $191 billion a year earlier. Neither figure is wrong. They count different things, and almost nobody quoting them says which.

What does each report actually count?

The e-Conomy SEA 2026 report, released 21 October 2026, puts the region's digital economy at a projected $368 billion in GMV for 2026, up 17 percent. Ecommerce is the largest single sector at $226 billion, measured across ten Southeast Asian countries. The Straits Times confirms the 2025 base of $191 billion.

Momentum Works, publishing its fourth annual Ecommerce in Southeast Asia report on 14 April 2026, counts differently. Its headline covers platform GMV only: $157.6 billion for 2025 across six core markets, plus an estimated $27.8 billion in non-platform ecommerce, for an all-channel total of $185.5 billion. There is no year in which the two reports publish the same quantity. The closest comparison is 2025 — $191 billion against $185.5 billion — a 3 percent gap that is not the one that matters.

Where did the platform share go?

Momentum Works' own series shows platform GMV falling from 89 percent of all ecommerce in 2024 to 85 percent in 2025. The missing 15 percent, roughly $27.8 billion, moves through brand sites, chat commerce and direct social selling that never touches a platform checkout.

Content commerce — livestream, short video and creator-driven selling — generated $49.7 billion in 2025, or 32 percent of platform GMV, up from 20 percent a year earlier. Nearly a third of what platforms book is now triggered by feeds rather than search, and the share escaping platforms entirely grows in the same direction. When Indonesia's Ministry of Trade replaced Permendag 31/2023 with Permendag 19/2026, signed 8 June 2026, it extended coverage to eight business models including ride-hailing and online travel, precisely because commerce had spread past the marketplaces the older rule assumed.

Why can't Indonesia's number be reconciled?

e-Conomy SEA 2025 put Indonesia's ecommerce GMV at $71 billion in 2025, about 72 percent of the country's digital economy. Momentum Works puts it at $57.7 billion, with growth of just 2.2 percent, slowed by Bukalapak's retreat from physical goods and Tokopedia's post-acquisition rationalisation under TikTok's control.

The gap is $13.3 billion, about 23 percent of the smaller figure — and each number is internally consistent. Indonesia at $71 billion of $191 billion is 37.2 percent of the region; at $57.7 billion of $157.6 billion it is 36.6 percent. Both reports agree Indonesia is roughly 37 percent of Southeast Asian ecommerce and disagree by 23 percent on the size of the whole. Neither publisher has published a bridge table reconciling the two, and no regulator has an interest in forcing one.

The growth table sharpens the point. On Momentum Works' numbers, 2025 growth ran: Thailand 51.8 percent, Malaysia 47.6 percent, the Philippines 32.0 percent, Vietnam 27.3 percent, Singapore 21.0 percent, Indonesia 2.2 percent. The 22.8 percent regional headline is an average no single large market matches, and Indonesia is the only one below it.

Is TikTok Shop really doubling?

Widely shared write-ups described TikTok Shop reaching $54.6 billion in 2025, doubled from $22.6 billion in 2024. That figure is TikTok Shop and Tokopedia combined — a merged entity at 65.7 percent of Shopee's GMV. TikTok Shop alone booked about $45.6 billion, roughly a 102 percent increase, while Tokopedia contributed roughly $9 billion after GMV rationalisation. Both "doubled" and "grew 54 percent" appeared in print in 2026, both defensible, one flattering.

Shopee booked $83.2 billion in 2025, a 53 percent platform share, growing 24.5 percent. The challenger's absolute add of about $19.2 billion exceeded the leader's $16.4 billion even as the leader kept its margin of scale. Lazada, the third of three platforms holding 98.8 percent of platform GMV, booked about $18 billion — a 28 percent fall in a market that grew 22.8 percent.

Ask for Shopee's Indonesian market share and the record offers four answers: APJII's survey puts user preference at 47.5 percent, down from 53.2 percent; Cube's panel puts it at 59 percent of platform GMV for 2025 and 55 percent in the first half of 2026, with TikTok Shop climbing from 31 to 39 percent; a scraping-based estimate puts it near 38 percent; a skincare-only dataset puts it at 62 percent. These measure four different things.

What does the seller actually pay?

Sea Limited's statements give the cost side GMV headlines omit: cost of services for Southeast Asian ecommerce reached $9.5 billion in fiscal 2025, and sales and marketing expense was $3.55 billion. Seller-side estimates put total operating deductions above 30 percent of selling price for many merchants. One percentage point of fees on Indonesia's $71 billion base is worth roughly $710 million a year.

The trigger was specific. On 18 May 2026, TikTok Shop raised its commission cap from Rp40,000 to Rp650,000 per item — more than fifteen-fold — and Shopee raised its free-shipping service fee in the same window. Indonesia's Minister of MSMEs said there must be no fee increases for now, and by 1 July 2026 the government and five platforms — Shopee, Tokopedia, TikTok Shop, Lazada and Blibli — agreed to postpone increases for small merchants.

The June regulations do not cap fees. Permendag 19/2026 requires fee transparency, seller consent with a 14-working-day objection window, priority for domestic products in search, and labels on AI-generated content. Permen UMKM 3/2026 orders at least a 50 percent service-fee discount for verified micro and small sellers, but implementation slipped from 1 August to end-October 2026. Around 42,000 local sellers were identified for the programme, against 22 million ecommerce merchants, fewer than 10 percent of whom hold a business identification number — the very credential the discount depends on.

What does AI commerce change?

The e-Conomy SEA 2026 survey of 9,006 AI users across six countries found 69 percent use AI to compare products and 75 percent would let AI agents find the best price and complete a purchase on their behalf. Trust is conditional: 44 percent want privacy safeguards, 36 percent want clear operating limits, 30 percent want the ability to undo an agent's actions.

Lazada's AI shopping assistant has roughly 100 million users, with assisted orders carrying average value about 75 percent higher; Shopee cites a 10 percent conversion lift from AI tools, and sellers using AI listing tools see 10 to 15 percent uplift. More than 8,000 Tmall brands joined Lazada since September, and about 330,000 vendors use its AI customer service.

The tension follows: an agent that buys where value is highest weakens the link between paying for visibility and making the sale. If a fraction of that 75 percent shifts to delegated purchasing, a cost stack already above 30 percent buys less, and the same GMV supports less platform revenue per order.

What should boards take from this?

No mathematical contradiction exists — every headline number fits its own denominators. What exists is definitional divergence reported as disagreement, scope ambiguity exploited by framing, and a real tension: 98.8 percent concentration alongside a 28 percent decline at number three, seller costs above 30 percent, and fee regulation without a cap. The 22.8 percent platform growth is real and sits on transaction records, not surveys. Anyone quoting $226 billion or $157.6 billion in a boardroom owes the room a denominator first.