Backblaze, Inc.
US ˙ NasdaqGM ˙ US05637B1052

SecurityBLZE / Backblaze, Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership304,905 shares
Latest Disclosed Value $ 1,051,922
Citadel Advisors Llc ownership in BLZE / Backblaze, Inc.

On May 15, 2026 - Citadel Advisors Llc filed a 13F-HR form disclosing ownership of 304,905 shares of Backblaze, Inc. (US:BLZE) valued at $1,051,922 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 140,062 shares of Backblaze, Inc.. This represents a change in shares of 117.69% during the quarter. The current value of the position is $2,366,063 USD.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (BLZE) in the form of stock options. The firm currently holds call options representing 0 of underlying shares valued at $0 USD and put options representing 24,000 of underlying shares valued at $82,800 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

BLZE / Backblaze, Inc. Historical Put/Call Ratio
Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date
Effective
Date
Form Security Class ID Avg Price
Paid (Est)
Reported
Shares
ΔShares ΔShares
(%)
Reported
Value
(x1000)
ΔValue
(%)
Alloc
(%)
ΔAlloc ΔAlloc (%) Cost Basis
(x1000)
Unrealized
Gain/Loss
(x1000)
2026-05-15 2026-03-31 13F BACKBLAZE COM CL A 05637B105 304,905 164,843 117.69 1,052 61.20 0.0002
2026-02-17 2025-12-31 13F BACKBLAZE COM CL A 05637B105 140,062 -320,142 -69.57 653 -84.73 0.0001
2025-11-14 2025-09-30 13F BACKBLAZE COM CL A 05637B105 460,204 256,423 125.83 4,271 281.25 0.0006
2025-08-14 2025-06-30 13F BACKBLAZE COM CL A 05637B105 203,781 -198,116 -49.30 1,121 -42.30 0.0002
2025-05-15 2025-03-31 13F BACKBLAZE COM CL A 05637B105 401,897 125,831 45.58 1,941 16.86 0.0004
2025-02-14 2024-12-31 13F BACKBLAZE COM CL A 05637B105 276,066 -3,699 -1.32 1,662 -7.05 0.0003
2024-11-14 2024-09-30 13F BACKBLAZE COM CL A 05637B105 279,765 151,039 117.33 1,788 125.63 0.0003
2024-08-14 2024-06-30 13F BACKBLAZE COM CL A 05637B105 128,726 36,562 39.67 793 -15.92 0.0002
2024-05-15 2024-03-31 13F BACKBLAZE COM CL A 05637B105 92,164 -2,414 -2.55 943 31.38 0.0002
2024-02-14 2023-12-31 13F BACKBLAZE COM CL A 05637B105 94,578 49,930 111.83 718 192.65 0.0001
2023-11-14 2023-09-30 13F BACKBLAZE COM CL A 05637B105 44,648 16,387 57.98 246 100.82 0.0001
2023-08-14 2023-06-30 13F BACKBLAZE COM CL A 05637B105 28,261 -30,976 -52.29 122 -59.20 0.0000
2023-05-15 2023-03-31 13F BACKBLAZE COM CL A 05637B105 59,237 26,699 82.05 299 49.50 0.0001
2023-02-14 2022-12-31 13F BACKBLAZE COM CL A 05637B105 32,538 -73,075 -69.19 200 -61.83 0.0000
2022-11-14 2022-09-30 13F BACKBLAZE COM CL A 05637B105 105,613 73,285 226.69 524 210.06 0.0001
2022-08-15 2022-06-30 13F BACKBLAZE COM CL A 05637B105 32,328 32,328 169 0.0000
2022-05-16 2022-03-31 13F BACKBLAZE COM CL A 05637B105 0 -10,981 -100.00 0 -100.00
2022-02-14 2021-12-31 13F BACKBLAZE COM CL A 05637B105 10,981 10,981 186 0.0000
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-02-17 2025-12-31 13F BACKBLAZE COM CL A Call 0 -100.00 0 -100.00 n/a n/a n/a
2025-11-14 2025-09-30 13F BACKBLAZE COM CL A Call 24,500 -25.08 227 26.82 n/a n/a n/a
2025-08-14 2025-06-30 13F BACKBLAZE COM CL A Call 32,700 -24.31 180 -13.94 n/a n/a n/a
2025-05-15 2025-03-31 13F BACKBLAZE COM CL A Call 43,200 1,036.84 209 845.45 n/a n/a n/a
2025-02-14 2024-12-31 13F BACKBLAZE COM CL A Call 3,800 -74.67 23 -76.84 n/a n/a n/a
2024-11-14 2024-09-30 13F BACKBLAZE COM CL A Call 15,000 -70.36 96 -69.45 n/a n/a n/a
2024-08-14 2024-06-30 13F BACKBLAZE COM CL A Call 50,600 -18.39 312 -50.95 n/a n/a n/a
2024-05-15 2024-03-31 13F BACKBLAZE COM CL A Call 62,000 171.93 634 266.47 n/a n/a n/a
2024-02-14 2023-12-31 13F BACKBLAZE COM CL A Call 22,800 32.56 173 84.04 n/a n/a n/a
2023-11-14 2023-09-30 13F BACKBLAZE COM CL A Call 17,200 4.88 95 32.39 n/a n/a n/a
2023-08-14 2023-06-30 13F BACKBLAZE COM CL A Call 16,400 -30.80 71 -40.34 n/a n/a n/a
2023-05-15 2023-03-31 13F BACKBLAZE COM CL A Call 23,700 64.58 120 35.23 n/a n/a n/a
2023-02-14 2022-12-31 13F BACKBLAZE COM CL A Call 14,400 -17.24 89 2.33 n/a n/a n/a
2022-11-14 2022-09-30 13F BACKBLAZE COM CL A Call 17,400 -34.59 86 -38.13 n/a n/a n/a
2022-08-15 2022-06-30 13F BACKBLAZE COM CL A Call 26,600 1.14 139 -50.53 n/a n/a n/a
2022-05-16 2022-03-31 13F BACKBLAZE COM CL A Call 26,300 -12.04 281 -44.36 n/a n/a n/a
2022-02-14 2021-12-31 13F BACKBLAZE COM CL A Call 29,900 505 n/a n/a n/a
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F BACKBLAZE COM CL A Put 24,000 45.45 83 7.89 n/a n/a n/a
2026-02-17 2025-12-31 13F BACKBLAZE COM CL A Put 16,500 77 n/a n/a n/a
2025-11-14 2025-09-30 13F BACKBLAZE COM CL A Put 0 -100.00 0 -100.00 n/a n/a n/a
2025-08-14 2025-06-30 13F BACKBLAZE COM CL A Put 33,300 -32.04 183 -22.46 n/a n/a n/a
2025-05-15 2025-03-31 13F BACKBLAZE COM CL A Put 49,000 252.52 237 184.34 n/a n/a n/a
2025-02-14 2024-12-31 13F BACKBLAZE COM CL A Put 13,900 -7.33 84 -12.63 n/a n/a n/a
2024-11-14 2024-09-30 13F BACKBLAZE COM CL A Put 15,000 -17.13 96 -14.41 n/a n/a n/a
2024-08-14 2024-06-30 13F BACKBLAZE COM CL A Put 18,100 376.32 111 192.11 n/a n/a n/a
2024-05-15 2024-03-31 13F BACKBLAZE COM CL A Put 3,800 171.43 39 280.00 n/a n/a n/a
2024-02-14 2023-12-31 13F BACKBLAZE COM CL A Put 1,400 180.00 11 400.00 n/a n/a n/a
2023-11-14 2023-09-30 13F BACKBLAZE COM CL A Put 500 -16.67 3 0.00 n/a n/a n/a
2023-08-14 2023-06-30 13F BACKBLAZE COM CL A Put 600 -97.93 3 -98.63 n/a n/a n/a
2023-05-15 2023-03-31 13F BACKBLAZE COM CL A Put 29,000 7,150.00 146 7,200.00 n/a n/a n/a
2023-02-14 2022-12-31 13F BACKBLAZE COM CL A Put 400 -98.99 2 -98.99 n/a n/a n/a
2022-11-14 2022-09-30 13F BACKBLAZE COM CL A Put 39,800 198 n/a n/a n/a
2022-05-16 2022-03-31 13F BACKBLAZE COM CL A Put 0 -100.00 0 -100.00 n/a n/a n/a
2022-02-14 2021-12-31 13F BACKBLAZE COM CL A Put 11,300 191 n/a n/a n/a
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.