- Steep rally: The Tesouro RendA+ 2075 government bond jumped more than 30% on the first business day following the first-round vote (October 5), according to Suno Notícias.
- Record drop in yields: The long-term yield curve at the 10-year vertex plummeted about 140 basis points in a single day—the sharpest daily compression since 2010.
- Fiscal repricing: The projected 10-year rate retreated from levels above 14% per year as the market adjusted the country's fiscal projections.
Brazilian fixed income experienced a historic moment on October 5, 2026: the Tesouro RendA+ 2075 government bond posted a gain of over 30% in a single trading session, according to analysis published by Suno Notícias. The catalyst for this surge was a drop of approximately 140 basis points in the long-term yield curve on the first business day following the first round of the presidential election.
Why Did Tesouro Direto Bonds Surge After the First Round?
The bonds rallied because the future interest rate curve dropped about 1.40 percentage points in a single day, driving up the prices of ultra-long-term bonds through mark-to-market accounting. As an analyst highlighted during a Suno Notícias broadcast on Sunday (October 25), this 100-plus basis point decline in the 10-year segment of the yield curve was the most intense daily compression observed in the Brazilian market since 2010.
The mechanics are straightforward and mathematical: when market interest rates fall, the unit price (PU) of previously issued government bonds must rise to rebalance the yield to maturity. The further away the bond's maturity date is, the higher its price sensitivity to fluctuations in future interest rates.
A turnaround in fiscal expectations drove the move. Before voters went to the polls in the first round, the market was pricing in interest rates above 14% per year for a 10-year horizon, reflecting a high risk premium demanded amid electoral uncertainties. With the election results in, analysts reassessed the future fiscal outlook, triggering a wave of relief in long-term yield premiums.
How Does Mark-to-Market Work in Fixed Income?
The atypical movement recorded by the Tesouro RendA+ 2075 clearly illustrates that fixed income is not a static investment immune to fluctuations. When an investor buys a fixed-rate or inflation-linked (IPCA+) government bond, the contracted return is only guaranteed if the bond is held in the portfolio until its final maturity date.
Extended horizons like 2075 experience multiplied daily price swings.
When interest rates drop, the bond's price on Tesouro Direto rises.
If interest rate projections climb, the bond's price suffers temporary losses.
Screen prices fluctuate daily. If an investor decides to sell the bond back to the National Treasury ahead of schedule, the amount received will be the exact market price at that moment. Bonds like the RendA+ line, designed with accumulation and conversion phases spanning decades, have an extremely long duration. For this reason, minor relief in market interest rates translates into large percentage jumps in bond prices.
What Could Happen to the Treasury After the Runoff Election?
The behavior of fixed income at the close of the electoral process will depend on how the market adjusts its inflation and government spending projections for the coming years. As the analysis featured on Suno Notícias emphasized, financial market prices are driven by constant shifts in expectations, rather than just consolidated data or accomplished facts.
If post-election fiscal signals point to spending control and budget responsibility, long-term yields could fall further, generating additional mark-to-market gains.
If there is political noise or renewed fiscal uncertainty, the market will demand higher premiums once again, causing a temporary drop in the screen prices of long-term bonds.
A 30% swing in a single day is the exception, not the rule. Yield compressions on the order of 140 basis points in 24 hours are rare episodes of rapid repricing. Investors who try to time these sudden shifts run the risk of entering just as rates have already fallen and the bulk of the one-time rally has passed.
What Changes for Retail Investors?
For anyone who holds or plans to hold Tesouro Direto bonds in their portfolio, understanding the root cause of this surge offers valuable practical lessons for building and managing fixed income investments.
If you hold the bond to its final maturity or until the income conversion phase, market volatility does not alter the yield agreed upon at purchase. However, for those looking to trade on mark-to-market movements, electoral cycles offer significant capital gain opportunities, but require the stomach to endure sharp drops in screen prices if the fiscal outlook deteriorates.
Fixed income also requires risk management. The illusion that the government bond market is calm and linear was dispelled on October 5. Extremely long maturities, such as bonds maturing in 2055, 2065, or 2075, exhibit volatility comparable to blue-chip stocks during crises or government transition periods.
Three Rules to Avoid Mistakes on Tesouro Direto During Electoral Periods
To navigate the post-election interest rate environment without compromising your capital, your strategy needs to align closely with your financial goals.
Match maturities to your goals — Use floating-rate bonds (such as Tesouro Selic) for your emergency fund and short-term cash. Long-term IPCA+ or RendA+ bonds should be reserved strictly for long-term capital and retirement.
Don't panic sell due to mark-to-market drops — If rates rise again and your bond's screen price falls, remember that a loss is only realized if you redeem early. By holding the bond to maturity, the contracted yield will be paid in full.
Avoid trying to time the market top — The gain of over 30% reported by Suno Notícias occurred immediately upon the reopening of post-election trading. Anyone who waited for news confirmation to buy long-term bonds had to settle for lower rates and more stretched prices.
The Verdict on Post-Election Fixed Income
The historic rally of over 30% in Tesouro RendA+ 2075 highlighted the power of mark-to-market accounting when interest rate expectations change abruptly in Brazil. For everyday investors, the main takeaway is to focus on the maturity date: take advantage of periods with high interest rates to lock in strong long-term yields and maintain discipline, without turning your fixed income portfolio into a day-trading desk driven by political headlines.