Short answer: On the current evidence, three contractors stand out as repeat offenders: Lockheed Martin (F‑35 — the single largest cost/readiness problem in the portfolio), Boeing (KC‑46 tanker — the worst self-inflicted fixed-price loss), and Northrop Grumman (Sentinel ICBM — the largest percentage cost breach, 81%+ over baseline). RTX (Raytheon) is the standout on the audit/fraud side rather than pure engineering overrun, having paid nearly $1 billion in 2024 to resolve DOJ/SEC findings of cost mischarging and bribery. None of this is peculiar to one firm, though: the Pentagon itself has failed its own financial audit for eight consecutive years (through FY2025), which is the backdrop against which all of these program-level figures sit.
Lockheed Martin — F‑35 (Joint Strike Fighter) - GAO's September 2025 assessment found the F-35 modernization effort (Block 4 / TR-3) plagued by cost growth and schedule slippage, with the "Global Sustainment Solution" reset now needing an estimated $13.7 billion more than planned through FY2031. - Total program life-cycle (acquisition + 77-year sustainment) cost estimate: over $2 trillion, with sustainment costs alone up 44% from $1.1 trillion (2018 estimate) to $1.58 trillion (2023 estimate). - Fleet readiness has fallen even as costs rise: mission-capable rate dropped from 67% (FY2021) to 44% (FY2025); full-mission-capable rate fell from 38% to 25% over the same period. - Delivery performance has worsened: Lockheed's 2024 deliveries averaged 238 days late (up from 61 days late in 2023) — yet the incentive-fee structure still let Lockheed collect large partial fees (GAO flagged roughly $1.7 billion paid out despite the poor readiness/lateness record) on late aircraft, which GAO explicitly called out as a design flaw rewarding non-performance. - DOD's FY2025 Agency Financial Report (the government's own failed 8th consecutive audit) specifically cited the Joint Strike Fighter Program's Global Spares Pool as a line item DOD "could not provide or obtain accurate and reliable data" to verify the existence, completeness, or value of — a direct, named audit failure tied to this program.
Boeing — KC‑46 Pegasus tanker - Under a fixed-price contract Boeing itself lobbied for, Boeing has absorbed essentially all cost overruns since contract award. Cumulative losses on the program are now roughly $8 billion, including a fresh $565 million charge disclosed in Boeing's Q4 2025 results (reported January 2026), on top of roughly $7 billion in prior losses. - Losses are attributed to Boeing's own supply-chain and production costs at its Everett, WA facility, not government scope changes — i.e., this is a program Boeing has structurally failed to execute profitably or on the technical requirements originally bid, and the Air Force has separately told Boeing to fix persistent technical deficiencies (notably the remote vision/boom system) before further orders. - Boeing also disclosed roughly $1.7 billion in combined defense-program losses in a single quarter (reported Jan 2025), spanning KC-46 and other fixed-price development programs (T-7A trainer, MQ-25, VC-25B "Air Force One"), indicating the overrun pattern is not confined to one program.
Northrop Grumman — Sentinel ICBM - The largest percentage cost breach among current major weapons programs: a Nunn-McCurdy "critical" breach in January 2024 at 37% over baseline, which subsequent re-estimates pushed to roughly 81% over the original ~$77.7 billion estimate — a total program cost now estimated at $140–160 billion. - The Air Force certified the program to continue (post-breach) but has since ordered work stoppages on portions of it and now expects at least a two-year schedule delay while the program undergoes a formal restructuring, which was still ongoing as of the most recent reporting.
RTX / Raytheon — audits, mischarging, and bribery (distinct from pure schedule/cost growth) - In October 2024, RTX's Raytheon subsidiary agreed to pay more than $950 million to resolve DOJ/SEC actions covering three separate matters: a $428 million civil settlement for allegedly misrepresenting labor and material costs to justify higher-priced no-bid contracts and for double-billing on a weapons maintenance contract; export-control violations; and foreign bribery in Qatar (paying a Qatari agent over $30 million to help secure a $510 million sole-source contract and other business). - This is the clearest recent example in the group of an actual proven audit/compliance failure (mischarging the government) rather than an honest cost/schedule estimate miss.
Also notable, for pattern-completeness - Ford-class carriers (Huntington Ingalls, prime shipbuilder): lead ship (CVN-78) grew from an ~$10.5 billion estimate to ~$13.3 billion delivered cost, with GAO attributing roughly $2.4 billion of the overrun to concurrent (immature) development of EMALS, the Advanced Arresting Gear, Dual Band Radar and the weapons elevators — GAO also found an 11-year stretch in which more than $15 billion was spent on the program without a single independent cost estimate. - Portfolio-wide: GAO's June 2025 Weapon Systems Annual Assessment found the 30 Major Defense Acquisition Programs assessed in both the current and prior report grew a combined $49.3 billion, and expected time to initial capability across MDAPs increased by 18 months in a single year (to nearly 12 years from program start) — so the Lockheed/Boeing/Northrop cases above are the sharpest examples of a broader, systemic pattern rather than isolated anomalies. - Pentagon-wide audit failure (context, not a contractor finding): DOD's FY2025 financial statements failed their audit for the eighth consecutive year, with 26 material weaknesses and 2 significant deficiencies identified — meaning the government's own books on these programs (including the F-35 spares example above) are independently unreliable, which limits how precisely any external party, including this analysis, can quantify contractor-level overbilling beyond the specific DOJ/GAO findings cited here.
Note: no chart was produced for this answer — the question asks for a qualitative, sourced comparison of documented program/contractor track records rather than a single quantitative series suited to a chart, and AskAmerica's own data warehouse does not carry a DCAA/DCMA audit-findings or program-cost-overrun table (confirmed via catalog search) to visualize from.