SPRO (Spero Therapeutics) Cyclically Adjusted PB Ratio: (As of Aug. 13, 2026)

Author: Vera Yuan Vera Yuan
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Director of Data and Quant Analytics at GuruFocus
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Dr. Charlie Tian is the founder and CEO of GuruFocus.com, a leading global investment research platform established in 2004. With a Ph.D. in physics, Dr. Tian transitioned from science to finance, applying a data-driven, disciplined approach to value investing.

SPRO Spero Therapeutics Inc SPRO
65 GF Score
Price $1.26
GF Value $1.04
Valuation Modestly Overvalued
! 4 Warning Signs
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What is Spero Therapeutics Cyclically Adjusted PB Ratio?

Note: If the price history is too short, we do not calculate current Cyclically Adjusted PB Ratio for this stock. All the historical data is shown as the company's primary share's data instead.

Shiller PE for Stocks: The True Measure of Stock Valuation


Spero Therapeutics  (NAS:SPRO) Cyclically Adjusted PB Ratio Explanation

Compared with the regular PB Ratio, which works poorly for cyclical businesses, the Cyclically Adjusted PB Ratio smoothed out the fluctuations of book value during business cycles. Therefore it is more accurate in reflecting the valuation of the company.

If a company has consistent business performance, the Cyclically Adjusted PB Ratio should give similar results to regular PB Ratio.


Spero Therapeutics Cyclically Adjusted PB Ratio Related Terms


Spero Therapeutics Cyclically Adjusted PB Ratio Historical Data

* Premium members only.

The historical data trend for Spero Therapeutics's Cyclically Adjusted PB Ratio can be seen below:

* For Operating Data section: All numbers are indicated by the unit behind each term and all currency related amount are in USD.
* For other sections: All numbers are in millions except for per share data, ratio, and percentage. All currency related amount are indicated in the company's associated stock exchange currency.

Spero Therapeutics Cyclically Adjusted PB Ratio Chart

Spero Therapeutics Annual Data
Trend Dec16 Dec17 Dec18 Dec19 Dec20 Dec21 Dec22 Dec23 Dec24 Dec25
Cyclically Adjusted PB Ratio
Get a 7-Day Free Trial Premium Member Only Premium Member Only 0.00 0.00 0.00 0.00 0.00

Spero Therapeutics Quarterly Data
Sep21 Dec21 Mar22 Jun22 Sep22 Dec22 Mar23 Jun23 Sep23 Dec23 Mar24 Jun24 Sep24 Dec24 Mar25 Jun25 Sep25 Dec25 Mar26 Jun26
Cyclically Adjusted PB Ratio Get a 7-Day Free Trial Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only 0.00 0.00 0.00 0.78 0.00

SPRO vs ACRV, BSEM, RNTX: Cyclically Adjusted PB Ratio Comparison

For the Biotechnology subindustry, Spero Therapeutics's Cyclically Adjusted PB Ratio, along with its competitors' market caps and Cyclically Adjusted PB Ratio data, can be viewed below:

* Competitive companies are chosen from companies within the same industry, with headquarter located in same country, with closest market capitalization; x-axis shows the market cap, and y-axis shows the term value; the bigger the dot, the larger the market cap. Note that "N/A" values will not show up in the chart.


Spero Therapeutics Cyclically Adjusted PB Ratio vs Biotechnology Industry

For the Biotechnology industry and Healthcare sector, Spero Therapeutics's Cyclically Adjusted PB Ratio distribution charts can be found below:

* The bar in red indicates where Spero Therapeutics's Cyclically Adjusted PB Ratio falls into.


SPRO
65GF Score
Spero Therapeutics Inc SPRO
Cyclically Adjusted PB Ratio is just one metric. See GF Score™, valuation, warning signs, and more.
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Spero Therapeutics Cyclically Adjusted PB Ratio Calculation

Like the Shiller PE Ratio, the Cyclically Adjusted PB Ratio takes the Book Value per Share from the past 10 years, adjusts it for inflation, and then calculates the average. This average is then used for the P/B calculation. Because it considers this 10-year average, it's often referred to as the CAPB Ratio.

The Shiller PE Ratio was first used by professor Robert Shiller to measure the valuation of the overall market. The similar calculation is applied by GuruFocus to calculate the Cyclically Adjusted PB Ratio.

Spero Therapeutics's Cyclically Adjusted Book per Share for the quarter that ended in Jun. 2026 is calculated as:

For example, Spero Therapeutics's adjusted Book Value per Share data for the three months ended in Jun. 2026 was:

Adj_Book=Book Value per Share/CPI of Jun. 2026 (Change)*Current CPI (Jun. 2026)
=0.763/333.9520*333.9520
=0.763

Current CPI (Jun. 2026) = 333.9520.

Spero Therapeutics Quarterly Data

Book Value per Share CPI Adj_Book
201609 0.000 241.428 0.000
201612 -2.800 241.432 -3.873
201703 0.000 243.801 0.000
201706 2.372 244.955 3.234
201709 -6.135 246.819 -8.301
201712 5.888 246.524 7.976
201803 5.188 249.554 6.943
201806 4.543 251.989 6.021
201809 6.886 252.439 9.110
201812 6.713 251.233 8.923
201903 6.517 254.202 8.562
201906 5.861 256.143 7.641
201909 4.966 256.759 6.459
201912 3.886 256.974 5.050
202003 4.055 258.115 5.246
202006 3.508 257.797 4.544
202009 5.113 260.280 6.560
202012 4.513 260.474 5.786
202103 4.006 264.877 5.051
202106 3.039 271.696 3.735
202109 3.473 274.310 4.228
202112 2.725 278.802 3.264
202203 1.907 287.504 2.215
202206 1.024 296.311 1.154
202209 0.758 296.808 0.853
202212 1.448 296.797 1.629
202303 1.233 301.836 1.364
202306 1.042 305.109 1.141
202309 1.013 307.789 1.099
202312 2.017 306.746 2.196
202403 1.787 312.332 1.911
202406 1.490 314.175 1.584
202409 1.206 315.301 1.277
202412 0.845 315.605 0.894
202503 0.605 319.799 0.632
202506 0.584 322.561 0.605
202509 0.470 324.800 0.483
202512 1.046 324.054 1.078
202603 0.914 330.213 0.924
202606 0.763 333.952 0.763

Add all the adjusted book value per share together and divide the count will get our Cyclically Adjusted Book per Share.

Please note that we use the CPI data of the country/region where the company is headquartered. If the CPI data for that country/region is not available, then we will use the CPI data of the United States as default.

Is Spero Therapeutics (SPRO) Overvalued in 2026?

Based on GuruFocus' analysis, Spero Therapeutics stock appears to be overvalued. The current stock price of $1.26 is trading 20.7% above its estimated GF Value™ of $1.04. GuruFocus considers Spero Therapeutics to be Modestly Overvalued.

Key valuation signals for SPRO:

  • Cyclically Adjusted PB Ratio:
  • GF Value™: $1.04 vs. price of $1.26 (20.7% above fair value)
  • GF Score™: 65/100 with 4 warning signs

No single metric tells the full story. See the SPRO stock analysis page for a complete view including 30-year financials, guru trades, and insider activity.


Spero Therapeutics Business Description

Other Exchanges 2HA:Germany
Address 675 Massachusetts Avenue, 14th Floor, Cambridge, MA, USA, 02139
Spero Therapeutics Inc is a clinical-stage biopharmaceutical firm. It focuses on identifying, developing, and commercializing novel treatments for MDR (Multi-drug-resistant) bacterial infections and rare diseases. The company's product candidate, tebipenem pivoxil hydrobromide or tebipenem HBr, is designed to be an oral carbapenem-class antibiotic for use in adults to treat MDR Gram-negative infections. It is also developing SPR720, a novel oral antibiotic designed for the treatment of a rare, orphan disease caused by pulmonary non-tuberculous mycobacterial infections, or NTM disease. It is also focused on SPR206, a next-generation polymyxin investigational product candidate being developed as an IV-administered medicine to treat MDR Gram-negative infections in the hospital.
65GF Score

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Cyclically Adjusted PB Ratio is just one metric. See GF Value™, 30-year financials, guru trades, warning signs, and more.

$1.26
Price
$1.04
GF Value