Go to Business Source Complete. Type a company name in the search box. On the side bar under Source Types, check the box next to SWOT Analyses.
You can also find a SWOT Analysis in ABI/INFORM Collection. Search "SWOT Analysis" (within quotations) and the name of the company. For example, you could search "SWOT Analysis" and nike. Materials will come from a variety of sources. If you need to narrow the results, look for the Source Type called "Reports".