Near 9:41 a.m. ET, the Dow was down 51 points, the S&P 500 was down four points, and the Nasdaq was down 20 points.
Stocks fell into the close on Monday after Greek's voted a resounding "No" during the weekend to the latest bailout package offered by creditors.
West Texas Intermediate crude oil is slightly lower after suffering its worst one-day plunge in several months on Monday. WTI was near $52.45 at the stock market open.
The euro fell another leg lower on Tuesday to around $1.0917. That's below the level it reached when it plunged Sunday after the Greek referendum result.
Treasuries are rallying this morning, and the yield on the benchmark 10-year note is down about six basis points at around 2.21% - a five-week low.
Tesla shares fell nearly 2% after Deutsche Bank analysts downgraded their rating from "Buy" to "Hold" even though they bumped their price target. The analysts wrote in a note that the company is expected to see massive growth from its cars and home batteries, but much of that is already accounted for in the stock price.
Shake Shack slid more than 5% at the open after Morgan Stanley analysts downgraded to "Underweight" from "Equal Weight" because shares are overvalued. In completely separate news, Shake Shack announced it's launching a chicken sandwich.