StockDriftsStockDriftsSeikagaku Corporation (4548) has 14 disclosed large-shareholding filings and 11 disclosed disposals on record, filed by 12 distinct investors. Together those filings cover ¥8.2B ($52.6M) in reported transaction value. The earliest filing StockDrifts holds for Seikagaku Corporation is dated 2021-09-24; the most recent is 2025-10-23. Across these filings the average return since disclosure is +2.67%, measured from each filing date to the latest available close.
| Date | Type | Source | Insider | Purpose | Shares | Price at filing | Return | Value |
|---|---|---|---|---|---|---|---|---|
| 2025-10-23 | BUY | Market Buy | 株式会社開生社 Kaiseisha Co., Ltd. | activist | 9.9M | ¥678 | -8.1% | ¥389M ($2.5M) |
| 2025-10-23 | BUY | Market Buy | 水谷 建 Ken Mizutani | activist | 483.3K | ¥678 | - | - |
| 2025-10-23 | BUY | Market Buy | 株式会社糖功 Toko Co., Ltd. | activist | 500.0K | ¥678 | - | - |
| 2025-10-23 | BUY | Market Buy | 新業株式会社 SHINGYO CO.,LTD. | activist | 7.8M | ¥678 | - | - |
| 2025-08-19 | BUY | Market Buy | 新業株式会社 SHINGYO CO.,LTD. | activist | 7.8M | ¥664 | - | - |
| 2025-08-19 | BUY | Market Buy | 株式会社開生社 Kaiseisha Co., Ltd. | activist | 9.3M | ¥664 | -6.2% | ¥8M ($49K) |
| 2025-08-19 | BUY | Market Buy | 株式会社糖功 Toko Co., Ltd. | activist | 500.0K | ¥664 | - | - |
| 2025-08-19 | BUY | Market Buy | 水谷 建 Ken Mizutani | activist | 483.3K | ¥664 | -6.2% | ¥4M ($24K) |
| 2025-08-18 | SELL | negotiated | 三菱UFJ信託銀行株式会社 Mitsubishi UFJ Financial Group Inc. | passive | 1.0M | ¥651 | +4.3% | ¥74M ($477K) |
| 2025-08-18 | BUY | negotiated | 三菱UFJアセットマネジメント株式会社 Mitsubishi UFJ Financial Group Inc. | passive | 354.7K | ¥651 | -4.3% | ¥18M ($119K) |
| 2025-08-18 | SELL | negotiated | 三菱UFJモルガン・スタンレー証券株式会社 Mitsubishi UFJ Morgan Stanley Securities Co., Ltd. | other | 30.8K | ¥651 | +4.3% | ¥70M ($453K) |
| 2025-08-18 | SELL | negotiated | 株式会社三菱UFJ銀行 Mitsubishi UFJ Financial Group Inc. | strategic | 536.7K | ¥651 | +4.3% | ¥651M ($4.2M) |
| 2025-08-14 | BUY | negotiated | 新業株式会社 SHINGYO CO.,LTD. | activist | 7.8M | ¥643 | - | - |
| 2025-08-14 | BUY | Market Buy | 水谷 建 Ken Mizutani | activist | 483.3K | ¥643 | -3.1% | ¥4M ($24K) |
| 2025-08-14 | BUY | Market Buy | 株式会社糖功 Toko Co., Ltd. | activist | 500.0K | ¥643 | - | - |
| 2025-08-14 | BUY | negotiated | 株式会社開生社 Kaiseisha Co., Ltd. | activist | 9.3M | ¥643 | -3.1% | ¥1.3B ($8.3M) |
| 2025-08-14 | BUY | negotiated | 水谷 建 Ken Mizutani | activist | 483.3K | ¥643 | -3.1% | ¥4M ($24K) |
| 2025-08-14 | BUY | negotiated | 株式会社糖功 Toko Co., Ltd. | activist | 500.0K | ¥643 | - | - |
| 2025-08-14 | BUY | Market Buy | 株式会社開生社 Kaiseisha Co., Ltd. | activist | 9.3M | ¥643 | -3.1% | ¥1.3B ($8.3M) |
| 2025-08-14 | BUY | Market Buy | 新業株式会社 SHINGYO CO.,LTD. | activist | 7.8M | ¥643 | - | - |
| 2025-08-06 | SELL | unknown | インベスコ・アセット・マネジメント株式会社 Invesco Asset Management (Japan) Limited | other | 2.7M | ¥656 | +5.0% | ¥380M ($2.5M) |
| 2025-03-21 | SELL | unknown | インベスコ・アセット・マネジメント株式会社 Invesco Asset Management (Japan) Limited | other | 3.3M | ¥790 | +21.1% | ¥426M ($2.8M) |
| 2025-03-21 | SELL | unknown | インベスコ ホンコン リミテッド Invesco Hong Kong Limited | other | 0 | ¥790 | +21.1% | ¥81M ($521K) |
| 2024-11-05 | BUY | Market Buy | 新業株式会社 SHINGYO CO.,LTD. | activist | 7.8M | ¥860 | - | - |
| 2024-11-05 | BUY | Market Buy | 株式会社開生社 Kaiseisha Co., Ltd. | activist | 7.3M | ¥860 | - | - |
| 2024-11-05 | BUY | Market Buy | 水谷 建 Ken Mizutani | activist | 476.1K | ¥860 | -27.6% | ¥5M ($32K) |
| 2024-11-05 | BUY | Market Buy | 株式会社糖功 Toko Co., Ltd. | activist | 500.0K | ¥860 | - | - |
| 2024-09-20 | SELL | unknown | インベスコ ホンコン リミテッド Invesco Hong Kong Limited | other | 99.9K | ¥836 | +25.5% | ¥19M ($123K) |
| 2024-09-20 | BUY | unknown | インベスコ・アセット・マネジメント株式会社 Invesco Asset Management (Japan) Limited | other | 3.8M | ¥836 | -25.5% | ¥3.2B ($20.5M) |
| 2024-09-03 | BUY | negotiated | 新業株式会社 SHINGYO CO.,LTD. | activist | 7.8M | ¥847 | - | - |
| 2024-09-03 | BUY | negotiated | 株式会社開生社 Kaiseisha Co., Ltd. | activist | 7.3M | ¥847 | - | - |
| 2024-09-03 | BUY | negotiated | 水谷 建 Ken Mizutani | activist | 476.1K | ¥847 | -26.4% | ¥5M ($31K) |
| 2024-09-03 | BUY | negotiated | 株式会社糖功 Toko Co., Ltd. | activist | 500.0K | ¥847 | - | - |
| 2024-07-29 | BUY | negotiated | 株式会社三菱UFJ銀行 Mitsubishi UFJ Financial Group Inc. | strategic | 1.5M | ¥881 | - | - |
| 2024-07-29 | SELL | negotiated | 三菱UFJ信託銀行株式会社 Mitsubishi UFJ Financial Group Inc. | passive | 1.1M | ¥881 | +29.3% | ¥130M ($840K) |
| 2024-07-29 | BUY | negotiated | 三菱UFJアセットマネジメント株式会社 Mitsubishi UFJ Financial Group Inc. | passive | 321.1K | ¥881 | -29.3% | ¥55M ($355K) |
| 2024-07-29 | BUY | negotiated | 三菱UFJモルガン・スタンレー証券株式会社 Mitsubishi UFJ Morgan Stanley Securities Co., Ltd. | other | 138.6K | ¥881 | - | ¥122M ($788K) |
| 2024-05-21 | BUY | unknown | インベスコ・アセット・マネジメント株式会社 Invesco Asset Management (Japan) Limited | other | 4.2M | ¥776 | -19.7% | ¥3.2B ($20.6M) |
| 2024-05-21 | SELL | unknown | インベスコ ホンコン リミテッド Invesco Hong Kong Limited | other | 124.7K | ¥776 | +19.7% | ¥22M ($142K) |
| 2023-12-15 | BUY | negotiated | 新業株式会社 SHINGYO CO.,LTD. | activist | 7.8M | ¥741 | - | - |
| 2023-12-15 | BUY | negotiated | 株式会社開生社 Kaiseisha Co., Ltd. | activist | 7.3M | ¥741 | - | - |
| 2023-12-15 | BUY | negotiated | 水谷 建 Ken Mizutani | activist | 471.2K | ¥741 | -15.9% | ¥25M ($163K) |
| 2023-12-15 | BUY | negotiated | 株式会社糖功 Toko Co., Ltd. | activist | 500.0K | ¥741 | - | - |
| 2021-09-24 | SELL | unknown | 株式会社みずほ銀行 Mizuho Bank, Ltd. | strategic | 1.6M | ¥1,131 | +44.9% | ¥450M ($2.9M) |
| 2021-09-24 | SELL | unknown | アセットマネジメントOne株式会社 Asset Management One Co., Ltd. | other | 957.7K | ¥1,131 | +44.9% | ¥276M ($1.8M) |
Every trade listed above comes from an official regulatory disclosure. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.