ATTO
ATTOCIK 0002058707
Small by assets
Assets $128M
as of Sep 6, 2026
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10-Q
Filed Sep 2, 2026
· Period ending Jun 30, 2026
Summary not yet generated.
8-K
Filed Sep 2, 2026
· Period ending Sep 2, 2026
Summary not yet generated.
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8-K
Filed Aug 6, 2026
· Period ending Aug 6, 2026
Summary not yet generated.
424B4
Filed Aug 5, 2026
Red flag
ATTO prices $289M IPO at $17/share; clinical-stage biotech to net $265.1M for pipeline
6 material changes detected. Sign up free to read the summary.
S-1/A
Filed Aug 4, 2026
ATTO upsizes IPO to 17M shares at $17, lifting net proceeds to $265.1M
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S-1/A
Filed Jul 29, 2026
Summary not yet generated.
S-1
Filed Jul 14, 2026
Summary not yet generated.
Latest financial statements
From 10-Q filed Sep 2, 2026 (period ending Jun 30, 2026). As printed on the EDGAR/iXBRL face — not generated by the model.
Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited)
(in thousands, except share and per share amounts)
| Description | Three months ended June 30, 2026 | Three months ended June 30, 2025 | Six months ended June 30, 2026 | Six months ended June 30, 2025 |
|---|---|---|---|---|
| Revenue | ||||
| Collaboration revenue | 450 | — | 450 | — |
| Total revenue | 450 | — | 450 | — |
| Operating expenses | ||||
| Research and development (including related party amounts of $178 and $34 for the three months ended June 30, 2026 and 2025, respectively, and $238 and $41 for the six months ended June 30, 2026 and 2025, respectively) | 18,946 | 13,588 | 35,692 | 25,444 |
| General and administrative (including related party amounts of $0 for the three months ended June 30, 2026 and 2025, and $0 and $239 for the six months ended June 30, 2026 and 2025, respectively) | 3,307 | 3,032 | 6,516 | 7,280 |
| Total operating expenses | 22,253 | 16,620 | 42,208 | 32,724 |
| Loss from operations | (21,803) | (16,620) | (41,758) | (32,724) |
| Other income (expense): | ||||
| Interest income | 1,141 | 2,041 | 2,467 | 3,167 |
| Change in fair value of preferred stock tranche liability | — | — | — | (170) |
| Other income (expense), net | (25) | 140 | (52) | 137 |
| Total other income (expense), net | 1,116 | 2,181 | 2,415 | 3,134 |
| Net loss | (20,687) | (14,439) | (39,343) | (29,590) |
| Less: Accretion of redeemable convertible preferred stock to its redemption value | — | — | — | (271) |
| Net loss attributable to common stockholders | (20,687) | (14,439) | (39,343) | (29,861) |
| Net loss per share attributable to common stockholders, basic and diluted | (4.88) | (3.71) | (9.38) | (7.75) |
| Weighted-average common shares outstanding, basic and diluted | 4,237,597 | 3,895,037 | 4,195,615 | 3,851,124 |
| Other comprehensive loss: | ||||
| Unrealized loss on available-for-sale marketable securities, net | (52) | (52) | (178) | (76) |
| Net loss and other comprehensive loss | (20,739) | (14,491) | (39,521) | (29,666) |
Condensed Consolidated Balance Sheets (Unaudited)
(in thousands, except share and per share amounts)
| Description | June 30, 2026 | December 31, 2025 |
|---|---|---|
| Assets | ||
| Current assets: | ||
| Cash and cash equivalents | 32,829 | 40,193 |
| Marketable securities | 82,303 | 112,075 |
| Prepaid expenses and other current assets | 3,269 | 4,027 |
| Total current assets | 118,401 | 156,295 |
| Restricted cash | 404 | 404 |
| Property and equipment, net | 3,343 | 3,492 |
| Operating lease right-of-use asset, net | 3,578 | 4,373 |
| Other non-current assets | 2,622 | 1,329 |
| Total assets | 128,348 | 165,893 |
| Liabilities, redeemable convertible preferred stock, and stockholders' deficit | ||
| Current liabilities: | ||
| Accounts payable (including related party amounts of $32 and $39 at June 30, 2026 and December 31, 2025, respectively) | 6,002 | 3,551 |
| Accrued expenses and other current liabilities | 4,575 | 5,535 |
| Operating lease liability, current portion | 2,038 | 1,921 |
| Total current liabilities | 12,615 | 11,007 |
| Operating lease liability, net of current portion | 2,288 | 3,341 |
| Other non-current liabilities | 678 | 755 |
| Total liabilities | 15,581 | 15,103 |
| Commitments and contingencies (Note 6) | ||
| Redeemable convertible preferred stock $0.0001 par value; 199,902,270 shares authorized, issued and outstanding at June 30, 2026 and December 31, 2025; aggregate liquidation preference of $255,850 at June 30, 2026 and December 31, 2025 | 258,226 | 258,226 |
| Stockholders' deficit: | ||
| Common stock $0.0001 par value; 284,023,000 shares authorized at June 30, 2026 and December 31, 2025; 4,529,100 and 4,507,108 shares issued and outstanding at June 30, 2026 and December 31, 2025, respectively | 1 | 1 |
| Additional paid-in capital | 4,972 | 3,474 |
| Accumulated other comprehensive (loss) income | (79) | 99 |
| Accumulated deficit | (150,353) | (111,010) |
| Total stockholders' deficit | (145,459) | (107,436) |
| Total liabilities, redeemable convertible preferred stock, and stockholders' deficit | 128,348 | 165,893 |
Condensed Consolidated Statements of Cash Flows (Unaudited)
(in thousands)
| Description | Six months ended June 30, 2026 | Six months ended June 30, 2025 |
|---|---|---|
| Cash flows from operating activities | ||
| Net loss | (39,343) | (29,590) |
| Adjustments to reconcile net loss to net cash used in operating activities | ||
| Stock-based compensation expense | 1,378 | 1,025 |
| Depreciation expense | 488 | 350 |
| Net accretion of discounts on marketable securities | (346) | (1,238) |
| Non-cash lease expense | 795 | 632 |
| Change in fair value of preferred stock tranche liability | — | 170 |
| Loss on disposal of property and equipment | — | 6 |
| Write-off of deferred offering costs | — | 393 |
| Changes in operating assets and liabilities: | ||
| Prepaid expenses and other current assets | 972 | 1,106 |
| Accounts payable | 3,159 | 2,174 |
| Accrued and other current liabilities | (1,124) | (1,335) |
| Operating lease liability | (936) | (175) |
| Other non-current assets | 25 | (215) |
| Net cash used in operating activities | (34,932) | (26,697) |
| Cash flows from investing activities | ||
| Maturities of marketable securities | 77,900 | 37,250 |
| Purchases of marketable securities | (48,174) | (138,823) |
| Purchases of property and equipment | (361) | (1,886) |
| Net cash provided by (used in) investing activities | 29,365 | (103,459) |
| Cash flows from financing activities | ||
| Proceeds from issuance of common stock upon exercise of stock options | 42 | 143 |
| Payments of deferred offering costs | (1,839) | (371) |
| Proceeds from issuance of Series B redeemable convertible preferred stock, net of issuance costs | — | 52,465 |
| Proceeds from issuance of Series C redeemable convertible preferred stock, net of issuance costs | — | 89,729 |
| Net cash (used in) provided by financing activities | (1,797) | 141,966 |
| Net change in cash, cash equivalents and restricted cash | (7,364) | 11,810 |
| Cash, cash equivalents and restricted cash at the beginning of the period | 40,597 | 31,239 |
| Cash, cash equivalents and restricted cash at the end of the period | 33,233 | 43,049 |
| Supplemental disclosures of noncash investing and financing activities | ||
| Deferred offering costs in accounts payable and accrued and other current liabilities | 709 | 4 |
| Vesting of early exercised stock options | 78 | 67 |
| Property and equipment purchases in accounts payable | 6 | 183 |
| Accretion of redeemable convertible preferred stock to its redemption value | — | 271 |
| Right-of-use asset obtained in exchange for operating lease liability | — | 5,771 |
| Settlement of preferred stock tranche liability upon issuance of Series B redeemable convertible preferred stock | — | 6,808 |
| Reconciliation of cash, cash equivalents and restricted cash: | ||
| Cash and cash equivalents | 32,829 | 42,645 |
| Restricted cash | 404 | 404 |
| Total cash, cash equivalents and restricted cash | 33,233 | 43,049 |
Amounts as printed on the EDGAR/iXBRL face — (in thousands, except share and per share amounts); (in thousands). Labels, columns, and figures are the filing face, not a GAAP stencil. Interactive statements & notes on EDGAR ↗