Hot IPO: Pinterest shares surged 28% to $24.40 in their debut on Thursday, the week's last day of trading, giving the online scrapbook company a market capitalization of $15.8 billion and signaling increased investor appetite for new tech listings.

Banking on more: Goldman Sachs shares fell 3.8% to $199.91 Monday despite reporting stronger profit for the first quarter than expected. Lighter trading activity during the first three months of the year meant that its revenue fell short of analysts' estimates. Shares closed the week at $205.91.

Spotty reception: Sprint fell 5.2% to $5.70 and T-Mobile slipped 3.5% to $71.49 Wednesday after a Wall Street Journal report cast doubt on the likelihood of government approval of the companies' $26.5 billion merger. Sprint finished the week at $5.77; T-Mobile landed at $73.75.

Low: Alliance Data Systems sank 9.3% to $164.04 Monday after it agreed to sell its Epsilon business to Publicis Groupe for $4.4 billion in cash, $1 billion less than what analysts at BMO Capital Markets expected. Shares closed the week at $162.60.

On track: Railroad operator CSX rose 5% to $79.73 Wednesday following better-than-expected quarterly earnings that showed revenue exceeding expectations and lower expenses. Shares closed the week at $78.97.

Hauling: Waste Management rose 2.4% to $104.26 Monday after it said it would buy its smaller rival, Advanced Disposal, for $3 billion and assume $1.9 billion of debt. The shares closed the week at $105.78. Advanced Disposal shares, up 17.8% to $31.99 on the news, finished at $32.83.