Despite the challenging December month, the S&P/TSX Composite Index rose 18% last year. The benchmark index has started this month positively, rising 0.8% in the first four days of trading. However, the slowdown in monetary easing initiatives by the United States Federal Reserve and uncertainty over the impact of Donald Trump's proposed tariffs on imports are causes of concern. Given the uncertain outlook, I believe the following three stocks would be excellent additions to your portfolio.

Celestica

Despite the uncertain outlook, I am bullish on Celestica (TSX:CLS) due to its exposure to the high-growth artificial intelligence (AI) sector. The company offers electronics manufacturing services (EMS) and supply chain solutions to customers worldwide. Amid the AI boom, investments in AI/ML data centres are rising, thus driving the demand for high-performance computing switches and storage units and expanding the addressable market for Celestica's products and services. Meanwhile, the company continues to innovate and launch new products to meet the growing needs of its customers.

Further, the rising defence budgets amid ongoing geopolitical tensions and recovery in commercial air travel could also support its financial growth in the coming quarters. Given its multiple growth drivers, I expect the uptrend in Celestica to continue irrespective of the broader market conditions, making it an excellent buy.

Waste Connections

Waste Connections (TSX:WCN) collects, transfers, and disposes of solid waste from secondary and exclusive markets across the United States and Canada. The company has expanded its footprint through organic growth and strategic acquisitions. The waste management company enjoys healthy margins despite its aggressive acquisition strategy due to lesser competition in secondary and exclusive markets. Supported by its solid financials, the company has returned around 460% at an annualized rate of 18.8%.

Moreover, WCN is continuing its acquisitions and constructing several renewable natural gas (RNG) and resource recovery facilities that could become operational in the coming years. Amid these growth prospects, the company's management projects its 2025 topline to grow at mid- to high single digits. Also, its adjusted EBITDA (earnings before interest, tax, depreciation, and amortization) could increase by high single digits. The company has also raised its dividends uninterruptedly since 2010 at an annualized rate of 14%. Considering all these factors, I believe WCN would be an ideal addition to your portfolio.

Enbridge

I have chosen Enbridge (TSX:ENB), a high-yielding dividend stock with consistent dividend growth for the previous 30 years, as my final pick. The diversified energy company earns around 98% of its cash flows from regulated assets and long-term contracts. So, its financials are less prone to market volatility, thus generating stable and predictable cash flows and raising its dividends consistently. It also offers an attractive forward dividend yield of 6.01%.

Moreover, Enbridge recently strengthened its financials by acquiring three low-risk natural gas utility assets in the United States. It also expects to put $6 billion of projects into service this year, boosting its financials. Along with these growth initiatives, the company focuses on cost optimization initiatives, which could improve its profitability. Amid these growth prospects, Enbridge's management projects its 2025 adjusted EBITDA to grow by 9.4%, thus making its future dividend payouts safer.