⚠ Mainstream: Renewables That Keep Writing DownModerate threat

Mitsui & Co. (8031) — threat to the moat

Mitsui has written down the same renewables developer three years running.

Mitsui invested in Mainstream Renewable Power, a developer of wind and solar projects. It recorded an equity-method impairment of ¥15.1 billion in the year to March 20241, a securities impairment of ¥15.9 billion in 2025, and impairments and loan valuation losses totalling ¥28,050 million in 20262.

Mainstream write-downs (¥ bn, years to March)15.1202415.9202528.12026Mitsui results, years to March 2024-2026
The charges grew each year.

Three consecutive years of write-downs on the same investment is a pattern, not an accident. Renewable developers have been hit by higher interest rates and rising costs, and Mainstream's projects have been worth less than expected.

For Mitsui, the lesson is that its infrastructure skill in contracted power and gas does not transfer automatically to development-stage renewables.

The contrast with the contracted power business is instructive. Mitsui's IPP portfolio sells 97% of its capacity under long-term contracts3 and earned ¥28.8 billion4. Mainstream develops projects before they have contracts, and that stage has cost Mitsui more than ¥59 billion in three years567.

The measure is any further charge. A fourth write-down would say the carrying value is still above what the business can earn.

References
  1. ReportedIt recorded an equity-method impairment of ¥15.1 billion in the year to March 2024, a securities impairment of ¥15.9 billion in 2025, and impairments and loan valuation losses totalling ¥28,050 million in 2026.
    Mitsui & Co., Consolidated Financial Results for the year ended March 31, 2024 - including the impairments in Italian and Texan oil and gas and the Anglo American Sur equity-method loss. — FY to March 2024 · publ. May 2024 · source ↗
  2. ReportedIt recorded an equity-method impairment of ¥15.1 billion in the year to March 2024, a securities impairment of ¥15.9 billion in 2025, and impairments and loan valuation losses totalling ¥28,050 million in 2026.
    Mitsui & Co., Consolidated Financial Results for the year ended March 31, 2026 (IFRS) - the JA Mitsui Leasing and Mainstream losses, the Russian LNG exposure, the Strait of Hormuz and the sensitivities. — FY to March 2026 · publ. 1 May 2026 · source ↗
  3. ReportedMitsui's IPP portfolio sells 97% of its capacity under long-term contracts and earned ¥28.8 billion.
    Mitsui & Co., results presentation for the year to March 2026 - producing assets with partners and stakes, LNG projects, affiliates and power contracts. — FY to March 2026 · publ. 1 May 2026 · source ↗
  4. ReportedMitsui's IPP portfolio sells 97% of its capacity under long-term contracts and earned ¥28.8 billion.
    Mitsui & Co. Integrated Report 2026, data section - the major affiliates by segment with ownership and share of profit. — FY to March 2022-2026 · publ. 2026 · source ↗
  5. ReportedMainstream develops projects before they have contracts, and that stage has cost Mitsui more than ¥59 billion in three years.
    Mitsui & Co., Consolidated Financial Results for the year ended March 31, 2024 - including the impairments in Italian and Texan oil and gas and the Anglo American Sur equity-method loss. — FY to March 2024 · publ. May 2024 · source ↗
  6. ReportedMainstream develops projects before they have contracts, and that stage has cost Mitsui more than ¥59 billion in three years.
    Mitsui & Co., Consolidated Financial Results for the year ended March 31, 2026 (IFRS) - the JA Mitsui Leasing and Mainstream losses, the Russian LNG exposure, the Strait of Hormuz and the sensitivities. — FY to March 2026 · publ. 1 May 2026 · source ↗
  7. Moat Explorer calcMainstream develops projects before they have contracts, and that stage has cost Mitsui more than ¥59 billion in three years.
    Moat Explorer calculation from Mitsui & Co.'s reported figures. Resource share of profit: (253.6 + 164.2) / 834.0 = 50.1% (2026), 51.0% (2025), 58.0% (2024). Iron ore business share: 262.2 / 834.0 = 31.4%. Trailing twelve months to June 2026: net income 833,971 - 191,647 + 294,052 = 936,376; revenue 13,995.2 - 3,299.9 + 4,347.6 = 15,042.9; EPS 291.12 - 66.68 + 103.73 = 328.17. P/S at March year-ends: 5,340.8 / 11,757.6 = 0.45 (2022), 0.44 (2023), 0.80 (2024), 0.55 (2025), 16,969.0 / 13,995.2 = 1.21 (2026). Share price change since March: 5,033 / 5,959 - 1 = -15.5%. Shares issued, split-adjusted: 3,284.7 million (March 2022) to 2,864.7 million (March 2026) = -12.8%. Equity-method profit and dividend income: 447.4 + 178.7 = 626.1, 57.6% of profit before tax of 1,087.1. Segment profit over segment assets, year to March 2026: Mineral & Metal Resources 253.6 / 4,313.2 = 5.9%; Machinery & Infrastructure 225.9 / 4,427.3 = 5.1%; Energy 164.2 / 4,181.4 = 3.9%; Chemicals 67.5 / 2,241.8 = 3.0%; Lifestyle 52.0 / 3,091.1 = 1.7%; Innovation & Corporate Development 59.0 / 2,655.3 = 2.2%; Iron & Steel Products 18.9 / 862.4 = 2.2%. Innovation & Corporate Development including other and adjustments: 59.0 + 20.7 - 27.7 = 51.9 (2026), 87.3 - 42.8 + 21.5 = 65.9 (2025), 53.8 + 5.6 - 5.9 = 53.6 (2024). A $10 move in iron ore: 10 x ¥3.0 billion = ¥30 billion, 3.3% of the ¥920 billion forecast. Berkshire's market value over cost: 8,785 / 3,490 = 2.52 times; dividend on cost 201 / 3,490 = 5.8%. Progress against guidance: 294.1 / 920.0 = 32.0%. Profit growth since the year to March 2016's loss: from -83.4 to 834.0. Resource profits: 335.1 + 281.7 = 616.8 (2024) and 253.6 + 164.2 = 417.8 (2026). Three largest segments: (253.6 + 225.9 + 164.2) / 841.1 = 76.5%. Energy Trading Singapore: 1,986,458 / 13,995,222 = 14.2%. First-quarter one-time gains: (44.2 + 10.2) / 294.1 = 18.5%. Innovation & Corporate Development first quarter against plan: 65.2 / 70.0 = 93%. Arctic LNG 2 provision change: 66,109 - 57,759 = 8,350. A $1 move in US gas: 10 x ¥1.2 billion = ¥12 billion. Vale dividend: 35.0 / 59.6 - 1 = -41%; 43.5 / 35.0 - 1 = +24%. Truck leasing holding: 19.8 / 28.4 - 1 = -30%; 18.8 / 19.8 - 1 = -5%. Profit to the 2029 target: 1,100 / 834.0 = 1.32; to the 2031 vision: 1,400 / 834.0 = 1.68. Berkshire value over cost 2.52 and dividend yield on cost 5.8%. Ministers North at full production: 7% x 20 Mt = 1.4 Mt. Mainstream charges: 15.1 + 15.9 + 28.05 = 59.05. Vale dividend fall against segment profit: (59.6 - 35.0) / 285.4 = 8.6%. Mitsui against smaller houses: profit 936.4 / 619.1 = 1.51 and 936.4 / 575.9 = 1.63; value 14.63 / 8.51 = 1.72 and 14.63 / 8.09 = 1.81. Trailing P/E: 14.63 trillion / 936.4 billion = 15.6; P/S 14.63 / 15.043 = 0.97. Dividend growth: 115 / 27.5 = 4.2 times. — FY to March 2026 · publ. September 2026 · source ↗
    Method: Arithmetic on figures reported in Mitsui & Co.'s results, integrated report, securities report and market data; operands shown in the source line.
Sources
Generated September 24, 2026