Bob donates $100/month to Club for Growth. He likes Americans for Prosperity almost as much—a dollar of Club for Growth funding is worth 90 cents of AFP to him. So for just $10, you can redirect Bob's entire $100 to AFP. Bob's happy. You spent $10 to move $100. That's Causeum.
Bob donates $100/month to Club for Growth. He values AFP at 90% as much. That means he'd switch his entire $100 to AFP if someone covered the 10% gap—just $10.
You're an AFP supporter. You spend $10 to cover Bob's gap. Bob switches. AFP gets $100 of new funding. You spent $10 to direct $100. Bob is no worse off—he got 90 cents of value per dollar either way. Club for Growth lost $100. AFP gained $100. You paid $10.
Another way to see it: Bob would redirect his $100 if $111.11 went to AFP instead, because $111.11 × 0.90 = $100—he's indifferent. You add $11.11 to Bob's $100 and AFP gets $111.11. Either way, roughly 10x leverage.
10x leverage on every dollar you spend. That's the power of matching donors who almost agree with you.
Causeum finds these matches automatically. You deposit money, buy stock in the causes you support, and set a price for each cause—how much a dollar of funding there is worth to you. The system does the rest, matching donors daily to maximize total impact.
When you deposit money and set your prices, the system builds you a portfolio. You might see $600 of Emily's List stock and $400 of Americans for Prosperity stock on your dashboard. Yield flows to those causes proportionally, every day. You own these positions and you can see them.
If you enable auto-trade, the system looks for beneficial matches once a day. Maybe tomorrow your portfolio shifts: you traded some Emily's List for 110% as much VoteVets stock, because a passionate VoteVets supporter funded the premium. Your dashboard shows the change, just like a robo-advisor rebalancing your portfolio.
Your $500 directed $1,340 of total funding to Emily's List this month.
That extra impact came from matching. The system found donors whose surplus could recruit you or others into more impactful positions.
Different people value causes differently, and those differences create opportunities. When one donor is willing to pay more per dollar of impact than another, there's a trade that makes everyone better off. Causeum finds those trades automatically.
Alice prices Americans for Prosperity at $1.00—she'll cover the whole dollar herself. Bob prices it at $0.70—he supports the cause but the cost feels steep.
Alice has $0.30 of surplus per dollar. The system uses part of Alice's surplus to subsidize Bob's purchase. Bob buys AFP stock at $0.70 out of pocket. Alice's surplus covers the remaining $0.30. AFP gets a full dollar of yield-generating stock.
Result: Alice's $1 didn't just fund her own position—it recruited Bob too. AFP gets more total funding than if each person had donated alone.
| Donor | EL Price | Cost per Dollar |
|---|---|---|
| Alice | $0.95 | $0.05 |
| Bob | $0.80 | $0.20 |
| Carol | $0.60 | $0.40 |
Alice and Bob donate $1 each. Emily's List gets $2 of annual yield. Combined surplus: $0.25.
Carol supports Emily's List but at $0.40 per dollar, the personal cost feels too steep. The system uses Alice and Bob's combined surplus to cover part of Carol's gap, bringing her in.
Result: Emily's List gets $2.75 of annual yield instead of $2.00. Nobody chose to subsidize anyone. The system found the efficient match automatically.
In most donation platforms, "donating" and "matching someone else's donation" are separate actions. Causeum unifies them into one thing: your price.
Everyone states one price per cause. If your price is higher than someone else's, your surplus automatically subsidizes their purchase—making cause stock cheaper for them. If your price is lower, you're the one being recruited. The system figures out who plays which role and executes the optimal set of matches.
There's no "subsidizer mode" to turn on. No separate matching budget to set. Your price implies everything. When nobody is available to recruit, your entire dollar goes directly to the cause. When there's someone cheaper to bring in, the system diverts part of your surplus to recruit them—because that generates more total impact per dollar.
There's a famous story about the British colonial government in India offering a bounty for dead cobras. Locals started breeding cobras to collect the bounty. When the government cancelled the program, the breeders released their stock. More cobras than ever.
The same trap exists in charitable giving. If you pay people to move their money away from a cause you dislike, you give people a reason to put money into that cause just to collect the payment. Every bounty on removal creates demand for the thing being removed.
You can never pay people to stop funding something. You can only make the alternatives more attractive.
Causeum avoids this trap with two structural rules.
First: subsidies are on the destination, not the origin. When someone's surplus makes VoteVets stock cheaper, that discount is available to everyone—regardless of what they held before. There's no bonus for leaving a specific cause. A bad actor who parks money in a cause they oppose, hoping to collect a premium for leaving, discovers there's no premium to collect. The discount is on VoteVets, not on departing anything. Going through another cause first accomplishes nothing.
Second: you can only ever withdraw what you paid. When Bob buys subsidized VoteVets stock at $0.70, the other $0.30 came from Alice's surplus. If Bob withdraws, he gets $0.70 back—exactly what he put in. Alice's $0.30 returns to her subsidy pool, ready to recruit the next donor. There's nothing to extract.
While your money sits in a cause fund, it earns interest for that cause every day. If you're a genuine supporter, that's the whole point.
But if someone parks money in a cause they don't support, hoping to game the system, every day they hold that position costs them real money. Interest is flowing to something they don't care about while they wait. It's a small cost—money market rates are modest—but it only penalizes bad actors. Honest donors pay nothing, psychologically.
When the system finds a beneficial match, it looks like this: you sell your Emily's List stock and receive 110% as much Americans for Prosperity stock. The extra 10% was funded by an AFP supporter's surplus. Your dashboard shows the rebalance just like a managed fund.
The key detail: your AFP position now carries a subsidy lien—a live obligation reflecting how much of your position is funded by someone else's surplus. This amount can change as the subsidizer updates their valuations. If they reduce their commitment, the lien shrinks, your out-of-pocket share rises, and the system may unwind the match if it's no longer worth it to you. If you exit, you repay the current lien. You walk away with exactly your current out-of-pocket share. The lien returns to the subsidizer's pool.
This means every match is self-correcting. If someone gets recruited into a position and then leaves, the subsidy flows back to the payer and recruits the next donor. The system only "spends" subsidy when someone holds long-term—which is exactly what supporters want.
Want to leave entirely? Just liquidate your positions. You get back what you paid, the liens stay with the causes, and the system re-optimizes tomorrow without you. Your principal was always yours.
When the system makes Americans for Prosperity stock cheap through efficient matching, people leave all kinds of other causes to take the deal—including causes you might not support. AFP gains funding and other causes lose it, simultaneously, from the same dollars.
This "double effect" is real and valuable. But it's emergent, never targeted. You can't aim the gravitational pull at specific causes. You just make your cause so attractive that people switch to it from wherever they were. The defunding happens as a side effect of making good causes compelling—which is exactly what keeps the mechanism safe from cobra breeding.
Understating your price risks getting skipped for cheaper donors. Overstating means you pay more than the cause is worth to you. You can shade your bid, but you don't know where the cutoff is—and shading too aggressively means missing the trade entirely.
The matching algorithm recruits the cheapest donors first, stretching every surplus dollar as far as possible. No alternative allocation produces more total cause funding.
Nobody can profit by faking support for a cause they don't believe in. Subsidies attach to the destination, not the origin, and you can only ever withdraw what you paid.
Every trade is voluntary through auto-trade opt-in. Your money is always yours, always redeemable at your out-of-pocket cost.
Every dollar sits in a money market fund. The platform's revenue comes from a small spread on matches and a modest management fee.
When someone exits a subsidized position, the lien returns to the subsidizer's pool and recruits the next donor. The system continuously re-optimizes.
When the system matches donors, there's a gap between what the subsidizer is willing to spend and what the recruit needs. Causeum keeps a small portion of that gap as a transaction spread, similar to how any exchange operates.
We also charge a modest annual management fee on total assets, comparable to any donor-advised fund. The incentives are clean: we make more money when there are more donors and more productive matches. We profit by making the system work well, not by extracting from participants.
You buy stock in the causes you believe in. Your money earns interest that flows to those causes as donations. You set a price per cause that says how much you'd contribute per dollar of impact. The system matches donors daily—using the surplus from people who price high to recruit people who price low. When you're matched, you might sell one cause's stock and receive more of another, with the premium funded by a passionate supporter. Subsidies are embedded in the stock and return to the subsidizer if you leave. You can always liquidate at what you paid out of pocket.
The result: every dollar in the system goes further than it would anywhere else.
Cause stock is not a security. It represents a tagged position in a money market fund whose yield flows to a designated 527 political organization.
Causeum's mechanism has been stress-tested against standard mechanism design critiques. Here's what holds up and what doesn't.
Causeum is a pay-as-bid market. You pay what you state. So naturally, people will shade their bids—understate their price hoping to get recruited at a discount, or overstate hoping to appear as a cheaper recruit. This is the same dynamic present in every commodity exchange, real estate market, and first-price auction. It's not a novel vulnerability. Shading is risky: understate too much and you get skipped in favor of genuinely cheaper donors. Overstate and you pay more than the cause is worth to you. You don't know where the cutoff is, so aggressive shading means missing the trade entirely.
If you genuinely want to fund AFP, depositing directly means you pay par. But you could instead park your money in a neutral cause, state a low AFP price, and wait to be recruited at a discount—getting $1 of AFP funding for $0.70 out of pocket. This is not extractive in a zero-sum sense. The subsidizer wanted to recruit someone into AFP. They succeeded. AFP got funded. But it creates real waste: the subsidizer paid a premium they didn't need to pay, and while you waited, yield flowed to the neutral cause instead of AFP. The defense is time and friction. Yield bleeding to a cause you don't care about is a real cost. Managing a parked position takes effort. For most users, the juice isn't worth the squeeze. At scale, this can be further mitigated by allowing downward-sloping demand curves (e.g., "I value the first $100 of AFP at $0.90 and the next $500 at $0.70") so the system can price-discriminate between a donor's first dollar and their hundredth.
We considered a Vickrey-Clarke-Groves mechanism, which would provide formal incentive compatibility—truthful reporting as a dominant strategy. VCG works by charging each participant the externality they impose on everyone else. It's theoretically elegant but practically fragile: it can run a budget deficit, produces counterintuitive prices under collusion, and nobody outside of academic economics understands it. More fundamentally, VCG requires irreversible payments to function (you can't undo a VCG transfer), which conflicts with the redeemable cause-stock model. The subsidy lien approach achieves cobra-prevention mechanically rather than through incentive design, which is simpler and more robust.
Could a bot rapidly cycle in and out of subsidized positions to drain liquidity? No. All matching settles in a single daily batch—you cannot cycle faster than once per day. Each cycle, the bot enters, gets matched, exits, repays the lien, and pays the transaction spread. The cause retains the lien. The bot loses the spread. Net result: the attacker loses money on every cycle. The atomic batch clearing makes this attack strictly unprofitable.
The transaction spread—how the platform generates revenue—prevents marginal trades from clearing. This is the same deadweight loss present in every exchange. It's a calibration problem, not a design flaw. Too large a spread kills marginal matches. Too small and the platform isn't viable. The AUM fee on the total money market pool provides baseline revenue that allows the spread to be kept small.