NEW YORK – A tough week on the stock market ended quietly Friday.

Major indexes notched modest gains, not nearly enough to make up for the four previous days of losses. It wound up being the second-worst week for the market so far this year.

The Dow Jones industrial average remains down slightly for 2015, and the Standard & Poor’s 500 index is essentially flat.

There was no one major catalyst to move the market one way or another Friday. Biotechnology stocks, battered over the last week, were among the top gainers, while energy stocks lagged as the price of oil fell.

Stocks fell most of the week due to a combination of weaker-than-expected economic data and concerns that the rapid rise of the dollar may crimp U.S. corporate earnings. Companies start releasing first-quarter results next month.

The question is whether the U.S. economy is really slowing down or whether the phenomenon can be blamed on the nasty winter weather. In addition to first-quarter earnings reports, investors will also be watching the Labor Department’s monthly job markets survey, due out April 3, for insight into how the economy is doing.

“I’m trying to be as forward-looking as possible here. Clearly the weather had some sort of impact this quarter, but I still believe U.S. economic growth is strong,” said Scott Wren, a global equity strategist at Wells Fargo Advisors.

The turmoil in Yemen has caused heightened volatility in oil markets this week as well. The tensions have erupted into a regional conflict, with Saudi Arabia and its allies bombing Shiite rebels allied with Iran, while Egyptian officials said a ground assault will follow the airstrikes. Iran denounced the Saudi-led air campaign, calling it “a dangerous step.”