{
  "observed_yields": {
    "kind": "observed_yield_levels",
    "source": "https://www.federalreserve.gov/releases/h15/",
    "release_date": "2026-09-11",
    "observation_dates": [
      "2026-09-04",
      "2026-09-10"
    ],
    "unit": "percent_per_annum",
    "series": "nominal_treasury_constant_maturity",
    "values": {
      "2 lata": [
        4.37,
        4.56
      ],
      "10 lat": [
        4.78,
        4.95
      ],
      "30 lat": [
        5.24,
        5.37
      ]
    },
    "not": [
      "coupon_rates",
      "bond_total_returns",
      "2026-09-11_close"
    ]
  },
  "price_scenarios": {
    "kind": "hypothetical_educational_calculation",
    "face_value": 100,
    "annual_coupon_percent": 4,
    "initial_yield_percent": 4,
    "elapsed_time_years": 0,
    "results": [
      {
        "years": 2,
        "prices_by_yield": {
          "0.03": 101.91346969554152,
          "0.04": 99.99999999999999,
          "0.05": 98.140589569161
        }
      },
      {
        "years": 10,
        "prices_by_yield": {
          "0.03": 108.53020283677581,
          "0.04": 99.99999999999997,
          "0.05": 92.27826507081517
        }
      },
      {
        "years": 20,
        "prices_by_yield": {
          "0.03": 114.87747486045546,
          "0.04": 99.99999999999994,
          "0.05": 87.53778965745997
        }
      }
    ],
    "price_formula": "sum(coupon/(1+y)^t, t=1..n) + face/(1+y)^n",
    "excludes": [
      "accrued_interest",
      "defaults",
      "fees",
      "taxes",
      "embedded_options"
    ]
  },
  "currency_examples": {
    "hypothetical": true,
    "usd_total_return": 0.05,
    "usd_pln_change": [
      -0.08,
      0.08
    ],
    "pln_returns": [
      -0.03399999999999992,
      0.13400000000000012
    ]
  },
  "real_return_example": {
    "hypothetical": true,
    "nominal_return": 0.05,
    "inflation": 0.06,
    "real_return": -0.009433962264150941
  },
  "refinancing_example": {
    "hypothetical": true,
    "debt": 10000000,
    "old_rate": 0.03,
    "new_rate": 0.07,
    "extra_annual_interest": 400000
  }
}