Blackstone Inc. is an American alternative investment management company based in New York City. Blackstone's private equity business has been one of the largest investors in leveraged buyouts in the last three decades, while its real estate business has actively acquired commercial real estate. Blackstone is also active in credit, infrastructure, hedge funds, insurance, secondaries, and growth equity. As of May 2024, Blackstone has more than US$1 trillion in total assets under management making it the largest alternative investment firm globally.

An alternative investment, also known as an alternative asset or alternative investment fund (AIF), is an investment in any asset class excluding capital stocks, bonds, and cash. The term is a relatively loose one and includes tangible assets such as precious metals, collectibles and some financial assets such as real estate, commodities, private equity, distressed securities, hedge funds, exchange funds, carbon credits, venture capital, film production, financial derivatives, cryptocurrencies, non-fungible tokens, and Tax Receivable Agreements. Investments in real estate, forestry and shipping are also often termed "alternative" despite the ancient use of such real assets to enhance and preserve wealth. Alternative investments are to be contrasted with traditional investments.