Buying amid a bear market and challenging market conditions can be difficult, as many top stocks are down big this year. News of cutbacks and layoffs don't inspire much confidence in the economy today. However, now can still be an advantageous time for long-term investors to load up on positions in companies that are no-brainer buys when looking at a time frame that spans years and decades rather than months.

Two stocks which fit that criterion and that risk-averse investors should consider adding to their portfolios today include Thermo Fisher Scientific (TMO 0.18%) and United Parcel Service (UPS 0.76%).

1. Thermo Fisher Scientific

Healthcare giant Thermo Fisher is a stalwart that you can rely on for the foreseeable future. What makes this a resilient investment to hang on to is that its operations are diverse. Thermo Fisher generates revenue from life sciences, analytical instruments, specialty diagnostics, as well as laboratory products and biopharma services, its largest segment.

Thermo Fisher has done an excellent job of growing its business, both organically and through acquisitions, over the years. In 2021 alone, the healthcare company closed on five deals, including a $17.4 billion purchase of PPD, a company that provides clinical research services to biotech businesses. Acquisitions boosted Thermo Fisher's sales by 19% in the second quarter. Revenue of $10.97 billion for the period ended July 2 rose organically but at a more modest rate of 3%.

Amid all this wheeling and dealing, Thermo Fisher has been able to consistently generate strong profits along the way, which is a good sign that it can effectively and efficiently integrate new businesses into its operations.

TMO Profit Margin (Quarterly) Chart

TMO Profit Margin (Quarterly) data by YCharts

Thermo Fisher's strong margins and excellent capital allocation over the years give it the kind of track record that long-term investors should desire from a business. Year-to-date, the stock is down around 10% (which is in line with how the S&P 500 has performed) and could be a good buy on the dip.

2. United Parcel Service

Another stock that's down this year but remains an excellent buy is United Parcel Service (UPS). It's down just 5% thus far, but it's another stalwart that should lead to strong returns over the years. The logistics business delivered encouraging numbers in its most recent quarter.

Consolidated revenue during the second quarter (ended June 30) rose 6% year-over-year to $24.8 billion. Meanwhile, operating profit gained 8.5% to $3.5 billion. Those are strong numbers at a time when e-commerce businesses have been struggling. Demand for UPS' services has remained strong, especially as the economy returns to normal. UPS generated more than 5% growth in both its international and U.S. domestic package segments last quarter. 

Over the past six months, the company has also brought in $8.3 billion in cash from its day-to-day operations, with free cash flow totaling $6.9 billion during that time frame. Those types of strong numbers enable the business to make moves to expand its operations. Earlier this month, UPS announced plans to purchase Bomi Group, which is a big name in healthcare logistics. The transaction will give UPS access to temperature-controlled facilities in 14 countries.

UPS is a solid buy, but at 16 times its future profits, it is a bit more expensive than rival FedEx, which trades at a multiple of just 10. However, the premium may very well be worth it as UPS' profit margin has been superior over the years:

UPS Profit Margin (Quarterly) Chart

UPS Profit Margin (Quarterly) data by YCharts

With a stronger bottom line, that could put UPS in a better position for the long haul to not just grow its business but its dividend as well -- which, at 3%, is also higher than the 2% yield FedEx provides.