Sterling vs. MasTec: Which Infrastructure Stock is the Better Buy?

The surge in U.S. energy, communications and large-scale development infrastructure spending is being driven by several structural trends that are likely to persist for years rather than quarters. With the explosion in AI-related data center development, the expansion of generation, transmission and distribution network projects has accelerated. Amid this backdrop, infrastructure companies such as Sterling Infrastructure, Inc. STRL and MasTec, Inc. MTZ are direct beneficiaries.Sterling is a diversified U.S. infrastructure services company, which is favoring from the multi-year demand growth visibility and is currently focused on stabilizing its market footing and prospects in the upcoming term through strategic organic or inorganic business efforts. Meanwhile, MasTec, which engages in the engineering, building, installation, maintenance and upgrade of energy, communication and utility, is working on expanding its margins and improving execution.Let’s closely compare the fundamentals of the two infrastructure stocks to determine which one is a better investment now.The Case for Sterling StockThis Texas-based infrastructure services provider started its 2026 journey with phenomenal financial performance amid favorable market trends. As mission-critical activity in data centers, advanced manufacturing and semiconductors grows, it is creating numerous project opportunities for the company. STRL ended first-quarter 2026 with a record $3.8 billion signed backlog and $5.15 billion combined backlog, representing year-over-year growth of 78% and 131%, respectively. Besides, its pipeline of high-probability future phase opportunities now exceeds $1.3 billion, bringing its visible work pool close to $6.5 billion. STRL’s CEC business has secured several large project awards since its acquisition, contributing $1.2 billion to the total backlog.The company’s inorganic moves are encouraging, as the acquired companies not only expand its market footing but also diversify its service portfolio and increase its growth trajectory. Sterling's acquisition of CEC has enhanced its ability to offer integrated site development and mission-critical electrical services under one roof. This strategy improves project coordination, execution efficiency and margin potential while making STRL a more valuable partner for hyperscale data center and semiconductor customers.Moreover, the recent acquisition of Stone Ridge Contracting, LLC expanded STRL’s geographic footprint in the Pacific Northwest and Texas. Stone Ridge is a Pocatello, ID-based heavy civil, concrete and construction management services provider with services stretching across sectors, including data centers, mining and industrial infrastructure. In 2026, Stone Ridge is expected to generate revenues between $180 million and $200 million, with EBITDA margins projected to be in the mid-teens.Alongside investing in growth opportunities, Sterling remains committed to enhancing shareholder value through disciplined capital deployment. It repurchased $12.3 million of shares during the first quarter of 2026, reflecting management's confidence in the business and its long-term earnings potential. STRL retains $362 million of share repurchase authorization and intends to be opportunistic after the first quarter’s buyback. Management also notes a richer pipeline of high-quality M&A targets compared with a year ago and cites significant balance sheet firepower. This setup supports selective acquisitions, internal capacity adds and buybacks without stressing leverage, helping cushion timing variability as backlog converts.The Case for MasTec StockMasTec is also gaining from sustained demand across multiple infrastructure end markets. Communications growth is supported by rising data consumption, fiber deployment and multiyear broadband initiatives, including BEAD funding. Power Delivery demand is driven by grid modernization, system hardening and rising electricity needs, with data centers expected to materially increase power consumption. Clean Energy and Infrastructure is seeing growth across renewables, industrial projects and mission-critical facilities, including data centers. This diversification reduces reliance on any single market and supports more stable long-term growth.Backlog reached a record $20.3 billion in the first quarter of 2026, increasing approximately 7% sequentially and 28% year over year, supported by a 1.4x book-to-bill ratio. Management highlighted that the backlog does not fully capture ongoing negotiations and verbal awards, indicating additional upside potential. It also highlighted growing opportunities in fiber interconnectivity, transmission infrastructure and turnkey data center construction, positioning MasTec at the center of several multiyear infrastructure trends.In the first quarter of 2026, MTZ’s adjusted EBITDA increased 73% year over year, with a margin expansion of 170 basis points. Power Delivery and Pipeline segments showed notable margin improvements, supported by better execution and project performance. MasTec expects continued margin expansion across segments in 2026, with full-year EBITDA guidance raised to approximately $1.5 billion and margins improving modestly. This reflects a better project mix, pricing improvements and operational discipline.However, variability in project timing, dwindling cash flow, increasing inflation risks and global political unrest are proving to be near-term growth restrictions for the company. MasTec operates in markets influenced by government policy and regulatory approvals. Renewable energy investment remains tied to policy frameworks and potential changes to incentive structures could impact project activity in Clean Energy and Infrastructure. These factors introduce uncertainty into project pipelines despite favorable long-term demand trends.Stock Performance & ValuationAs witnessed from the chart below, in the year-to-date period, Sterling’s share price performance has significantly outperformed MasTec's and the broader Construction sector.Image Source: Zacks Investment ResearchConsidering valuation, over the last five years, Sterling has been trading above MasTec on a forward 12-month price-to-earnings (P/E) ratio basis.Image Source: Zacks Investment ResearchOverall, from these technical indicators, it can be deduced that STRL stock offers an accelerating growth trend but with a premium valuation, while MTZ stock offers a diminishing growth trend with a discounted valuation.Comparing EPS Estimate Trends: STRL vs. MTZThe Zacks Consensus Estimate for STRL’s 2026 and 2027 earnings has trended upward in the past 30 days to $19.31 per share and $27.43 per share, respectively. The estimates for 2026 and 2027 imply year-over-year growth of 77.5% and 42.1%, respectively.STRL's EPS TrendImage Source: Zacks Investment ResearchThe Zacks Consensus Estimate for MTZ’s 2026 and 2027 earnings has trended upward in the past 60 days to $8.86 per share and $11.77 per share, respectively. The revised estimated figures for 2026 and 2027 imply 35.3% and 32.8% year-over-year growth, respectively.MTZ's EPS TrendImage Source: Zacks Investment ResearchReturn on Equity (ROE) of STRL & MTZ StocksSterling’s trailing 12-month ROE of 37.02% significantly exceeds MasTec’s average, underscoring its efficiency in generating shareholder returns.Image Source: Zacks Investment ResearchInvestment Decision: Choosing Between STRL Stock & MTZ StockBoth Sterling and MasTec are benefiting from the multiyear U.S. infrastructure buildout tied to AI data centers, power demand, broadband expansion and industrial development. However, based on the growth metrics, earnings momentum and technical indicators, Sterling appears to have the stronger investment case today.Sterling’s exceptional execution efforts and backlog momentum, supported by strong demand from data centers, semiconductor fabs and advanced manufacturing projects, alongside the acquisitions of CEC and Stone Ridge, boost its upcoming growth prospects. Management’s raised 2026 outlook, expanding buyback authorization and robust M&A pipeline further reinforce confidence in long-term growth. Additionally, EPS estimates imply growth of 77.5% in 2026 and 42.1% in 2027, while ROE stands at an impressive 37%.MasTec also remains well positioned, with a record $20.3 billion backlog, improving margins and exposure to communications, power delivery and clean energy markets. Earnings estimates are moving higher, and valuation remains more attractive than Sterling’s. However, project timing risks, regulatory uncertainty surrounding renewable energy investments and weaker cash-flow trends temper the near-term outlook.That said, Sterling’s superior stock performance, faster earnings growth, stronger ROE and clearer exposure to high-growth AI infrastructure markets outweigh its premium valuation. Thus, with a Zacks Rank #1 (Strong Buy) versus MasTec’s Zacks Rank #3 (Hold), STRL stock emerges as the better stock to buy now for investors seeking growth, while MTZ stock may appeal more to value-oriented investors willing to accept a slower growth trajectory. You can see the complete list of today’s Zacks #1 Rank stocks here.Radical New Technology Could Hand Investors Huge GainsQuantum Computing is the next technological revolution, and it could be even more advanced than AI.While some believed the technology was years away, it is already present and moving fast. 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