This month’s data reveals a landscape in three distinct tiers. At the top, SaaS and finance brands continue to own the saturation play, by repeating the same sponsor slot across 10+ newsletters in their category. In the middle, a new tier of B2C and creator-economy brands is emerging, buying deliberately across specific newsletters. At the bottom, a massive gap: culture and entertainment newsletters remain almost entirely unmonetized, despite housing some of Substack’s most engaged niche audiences.
↑ Moving up
Poshmark is running a strategy, not a campaign. Over the last 30 days, the resale platform has landed confirmed paid partnerships across at least three creator newsletters: Erika Veurink’s Long Live (fashion), Tori Simokov’s Window Seat (travel/lifestyle), and Jennifer Cook’s mom friend (parenting). What's smart: Poshmark didn't pick random fashion writers. Each of these writers had already mentioned Poshmark organically in their archives. Readers already trusted their take on resale and shopping. The sponsorships formalize what was already working. Each post is clearly disclosed, yet Poshmark reads native to the writer's voice because, in a real sense, it already belonged there. That consistency across three unrelated newsletters, each written in the writer's own style, suggests the brand isn't testing. It's building a roster of writers who were already advocates.
Pique is running the same pattern, but with a different structure. The tea brand has landed 8+ placements over the past nine months, with Beth Bollinger’s Nest Wellness as the clear anchor. They sponsor Beth's newsletter consistently, across seasons and formats (product roundups, recipes, wellness guides). That consistency signals something: Pique found an audience that converts and keeps coming back. More recently, they've expanded to 4 other wellness and lifestyle newsletters: Julie Fratantoni, PhD’s Better Brain, Mia Rigden’s Btwn Meals, Ben Caplan, MD’s Doctor Approved. They’ve clearly found something that works and are expanding to similar audiences.
Brand spotlight: Tracksuit
A B2B brand finding its exact niche on Substack
Tracksuit, a brand intelligence and tracking tool, has landed 11 confirmed placements across three publications in the last 30 days: Because of Marketing, The Brand Waves, and Brand Baby. All three are newsletters specifically about how brands show up—strategy, campaigns, partnerships, trends.
Tracksuit has been sponsoring consistently since September, nine months of repeat placements. They’re not testing anymore. That's a brand that's found a channel that works and is doubling down. For a B2B software tool, Substack sponsorships often read as experimental. Tracksuit treating it as a core acquisition channel signals something: this audience converts.
↓ Cooling and consolidating
Tech/SaaS saturation deepens. Brex, Mercury, Public, Deel, Attio remain the anchor sponsors for founder and builder newsletters. The repeats are getting tighter (same publication, same slot, weekly), which suggests these brands have found their core channel and are optimizing rather than expanding.
Culture and entertainment remains the gap. We've now mapped 40+ culture, art, and entertainment newsletters on Substack, including: Chartbook, Garbage Day, Secret Strategist, The Bear Cave. Combined, they reach some of Substack's most engaged and affluent readers. Across that entire segment, paid sponsorship penetration sits around 25-30%. For comparison: tech newsletters run 89% penetration. Lifestyle and home run 60%.
That gap is either massive opportunity or a signal that culture and entertainment audiences resist commercialization. Probably both.
The watchlist: Really Rich
A 15K personal finance letter, explosive growth, zero sponsors
Helena Di Biase launched Really Rich in July 2025 and just added 40K subscribers in the last 32 days- a 40% growth spike. The newsletter covers money, business, health, and relationships with hundreds of paid subscribers already on board. Zero sponsorships so far.
That growth rate matters because we’ve already mapped real brand activity in adjacent categories: health brands (Pique, Needed) and wealth-building tools (finance/investing platforms). Helena’s audience is exactly the demographic those brands want to reach. The question isn’t whether Really Rich will monetize. It’s whether she’ll choose to, and which brands will move first.
For a wellness, finance, or business-focused brand, she’s the kind of writer to watch before she becomes unavailable.
Subs 15K · Paid subscribers hundreds · Organic mentions TBD · Paid 0
What’s shifting
Last month we called the B2C opportunity ‘uncaptured.’ We are slowly starting to see that shift, with brands like Poshmark and Pique. They’ve found their audiences here and are engaging in unique ways to reach them.
Substack formalized this in June with an official sponsorship program, but there’s an important asterisk: the program only surfaces creators with 100+ paid subscribers. That structure leaves a massive opportunity untouched. A newsletter with 8K total subscribers but only 50 paid subs won’t show up in Substack’s directory for sponsorships. But for the right brand, one looking for a specific, high-trust audience, that 8K list is worth far more than a broad 100K. The direct brand deals, the ones Poshmark and Pique are already running, will stay the real opportunity.
The Pulse is a monthly read of the Substack brand layer: who’s running paid placements, what patterns are emerging, and which newsletters brands should be watching. From In House.
Thanks for the shoutout Alexandra, made my day 💜
I've loved working with Tracksuit – I think they're crushing the Substack game by partnering with niche publications specifically reaching their audience of brand marketers. Loved this breakdown!