Rho Treasury vs Mercury Treasury

Last updated 2026-10-17. Rates snapshot 2026-10-16; each figure carries the provider's own as-of date and links to its source.

Both quote yields net of a 0.15%–0.60% annual fee that falls as balances grow. Rho's minimum is $50K and it offers 13-week T-Bills as well as a government money market fund and an ultra-short fund; Mercury's Treasury unlocks at $250K with a money market fund or an ultra-short bond fund.

Quick read (data checked 2026-10-17): Mercury shows the higher headline yield: 4.05% vs 4.03%. Mercury shows the higher entry-tier yield: 3.28% vs 3.21%. Minimums: Rho $50,000; Mercury $250,000 across Mercury accounts. Both are securities products, protected by SIPC rather than FDIC, so they can lose value.

What you'd earn at your balance

Balance	Rho	Mercury
$100K	3.21% Gov't MMF (IJTXX) · 3.43% Ultra-short (MULSX) · 3.58% 13-week T-Bills	Not eligible (minimum: $250,000 across Mercury accounts)
$500K	3.21% Gov't MMF (IJTXX) · 3.43% Ultra-short (MULSX) · 3.58% 13-week T-Bills	3.28% Gov't MMF (MRGXX) · 3.60% Ultra-short bonds (MCRYX)
$1M	3.21% Gov't MMF (IJTXX) · 3.43% Ultra-short (MULSX) · 3.58% 13-week T-Bills	3.28% Gov't MMF (MRGXX) · 3.60% Ultra-short bonds (MCRYX)
$5M	3.46% Gov't MMF (IJTXX) · 3.68% Ultra-short (MULSX) · 3.83% 13-week T-Bills	3.53% Gov't MMF (MRGXX) · 3.85% Ultra-short bonds (MCRYX)
$25M	3.66% Gov't MMF (IJTXX) · 3.88% Ultra-short (MULSX) · 4.03% 13-week T-Bills	3.73% Gov't MMF (MRGXX) · 4.05% Ultra-short bonds (MCRYX)

Net published yields at each balance, as the providers print them. How the tier is set:

Rho: Total Rho deposits (fee tier); $50K minimum investment

Mercury: Total deposits across all Mercury accounts; Treasury requires $250K

Side by side

	Rho	Mercury
Product	Rho Treasury	Mercury Treasury
Type	13-week T-Bills, JPMorgan gov't MMF (IJTXX), Morgan Stanley ultra-short (MULSX)	Gov't money market fund (MRGXX) and ultra-short bond fund (MCRYX)
Headline yield (up to)	4.03%	4.05%
Entry-tier yield	3.21%	3.28%
Yield detail	$50K–2M: 3.21% MMF / 3.43% MULSX / 3.58% T-Bill · $20M+: 3.66% / 3.88% / 4.03% (net of fees; T-Bill = Rho 7-day average YTM; Rho also prints a second T-bill figure, e.g. 3.52% / 3.97%)	$250K–2M: 3.28% MMF / 3.60% ultra-short · $20–50M: 3.73% / 4.05% (net of fees)
Yield as of	2026-10-17 (T-Bill avg YTM); IJTXX 2026-10-16	2026-10-09 (re-checked 2026-10-17, unchanged)
Minimum	$50,000	$250,000 across Mercury accounts
Fees	0.15%–0.60%/yr AUM fee (yields shown net)	0.15%–0.60%/yr of Treasury positions (yields shown net)
Liquidity	IJTXX same day before cutoff; T-Bills & other funds 2 business days (3 after cutoff)	MMF same day if by 3pm ET; ultra-short 1–2 business days (up to 4)
Protection	SIPC up to $500K (incl. $250K cash) via Apex / Interactive Brokers; not FDIC. Separate savings: up to $75M FDIC sweep	SIPC up to $500K (incl. $250K cash) via Apex Clearing; not FDIC. Checking/savings: up to $5M FDIC via sweep
Source	Rho page	Mercury page

How to choose

Check eligibility first. A higher top-tier rate doesn't help if your balance is below the minimum or the top tier.
Compare like with like. A money market fund's 7-day yield, a T-Bill's yield to maturity and a bond fund's yield are different measures. See methodology.
Mind liquidity. Keep payroll-and-vendor cash in an operating account; only move cash you won't need for a while. See where to keep startup cash.

FAQ

Which pays more, Rho or Mercury?

It depends on balance. Mercury shows the higher headline (top-tier) yield: 4.05% vs 4.03%. Mercury shows the higher entry-tier yield: 3.28% vs 3.21%. See the balance table on this page for each tier.

Is Rho Treasury FDIC insured?

Rho: SIPC up to $500K (incl. $250K cash) via Apex / Interactive Brokers; not FDIC. Separate savings: up to $75M FDIC sweep.

Is Mercury Treasury FDIC insured?

Mercury: SIPC up to $500K (incl. $250K cash) via Apex Clearing; not FDIC. Checking/savings: up to $5M FDIC via sweep.

What is the minimum for Rho and Mercury?

Rho: $50,000. Mercury: $250,000 across Mercury accounts.

How fast can I get the money back?

Rho: IJTXX same day before cutoff; T-Bills & other funds 2 business days (3 after cutoff). Mercury: MMF same day if by 3pm ET; ultra-short 1–2 business days (up to 4).

All providers: rates table · current startup treasury rates · all guides

Not financial advice. IdleCash is an independent, informational comparison. We are not a bank, broker or adviser. The comparison table is always sorted purely by the data; sponsorship never changes rank. Yields are variable, quoted as each provider advertises them, and may have changed. Securities products are not FDIC-insured and can lose value. Verify on the provider's site before acting.