{
  "checked_on": "2026-10-03",
  "toy_bond": {
    "description": "Fictional $100 payment in 10 years; annual compounding",
    "price_at_4_pct": 67.5564168826,
    "price_at_3_5_pct": 70.891881371,
    "instantaneous_price_change_pct": 4.9373022465,
    "duration_approx_price_change_pct": 4.8076923077
  },
  "official_observations_source": "https://home.treasury.gov/resource-center/data-chart-center/interest-rates/pages/xml?data=daily_treasury_yield_curve&field_tdr_date_value=2010",
  "observed_changes": {
    "10_year_2010_11_02_to_03_bps": 4,
    "10_year_2010_11_03_to_04_bps": -14,
    "10_year_2010_11_02_to_04_bps": -10,
    "spread_2010_11_02_to_04_bps": -9
  },
  "interpretation": "Descriptive daily par yields; no causal effect or strategy return"
}