At the recent BTC++, developer Calle presented the latest progress on Cashu, a privacy-preserving eCash protocol that uses blind signatures to enable bearer-style Bitcoin payments. The project has grown rapidly since 2023, spawning multiple wallet and mint implementations in Python, Go, and Rust—including CDK (Cashu Development Kit) and Coco, a stateful TypeScript library that makes integrating Cashu into web and mobile apps simple. “You basically fully understand Cashu’s cryptography if you understand this little piece of math,” Calle noted, explaining how blinding and unblinding create untraceable digital coins. The talk outlined integrations with Lightning Network for atomic swaps, multi-mint payments, and gateways that allow eCash to move across Lightning without revealing activity to mints. Calle notes ongoing research occuring in “reverse multinet” payments and offline preimage handling, inviting developers to “help us solve these problems.”
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David Puell of ARK Invest argues that most investors underestimate Bitcoin’s portfolio value because they equate its volatility with risk rather than distinguishing between upside and downside movement. Puell applies three metrics, the Sharpe, Sortino, and Omega ratios, to assess Bitcoin’s historical risk-adjusted performance. While the Sharpe Ratio shows strong long-term returns relative to volatility, the Sortino and Omega ratios, which only penalize downside variance, paint a far more favorable picture. As of mid-September 2025, Bitcoin’s Sortino Ratio stood at 3.2, nearly double its Sharpe of 1.7, and its Omega Ratio indicated upside returns outpacing downside by 29%. Portfolio simulations from 2015–2024 show the Sortino and Omega frameworks consistently recommending 8–9% Bitcoin allocations, compared to lower Sharpe-based allocations. Puell concludes that “the rewards have been worth the risk,” suggesting Bitcoin’s volatility reflects opportunity, not instability, within diversified digital asset portfolios.
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Walmart-backed fintech app OnePay plans to introduce bitcoin trading and custody later this year, as CNBC reported. The expansion, powered by infrastructure firm Zerohash, will allow millions of Americans to buy, sell, and spend bitcoin directly from their smartphones. Founded in 2021 by Walmart and Ribbit Capital, OnePay has grown into a multi-service financial platform offering savings, cards, BNPL loans, and mobile plans. Its integration with Walmart’s in-store and online checkout gives it a unique advantage over rivals like PayPal and Cash App. Analysts told CNBC the move could make OnePay “America’s first true super app,” mirroring platforms like China’s WeChat by merging payments, shopping, and banking. Bitcoin use could soon be as seamless as scanning at checkout, evidence, as CNBC’s Hugh Son noted, that digital assets are now viewed as “core offerings” within mainstream financial services.
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Bitcoin miner Marathon Digital Holdings (MARA) has sold nearly half of its monthly bitcoin production for the first time in 16 months, signaling a strategic shift as miners adapt to tightening margins. In its September report, MARA disclosed it sold 49.32% of the 736 BTC mined, ending its “full hodl” streak that began in May 2024. The move follows a period of rising network difficulty that has compressed hashprice and pressured miner profitability. Despite the sales, MARA’s operational strength improved: its realized hashrate climbed 15.1% month-over-month to 53.3 EH/s, or 88.3% of installed capacity, capturing 5.15% of global bitcoin block rewards. The firm now holds 52,850 BTC worth about $6.3 billion. Analysts say the decision likely reflects prudent liquidity management and reinvestment strategy as the digital asset industry adjusts to higher competition and lower block subsidies.
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