Zipcar and Arcos Dorados lead this week's dynamic US IPO market

The US IPO market strengthened this week with seven companies approaching the public markets within two days.

Four deals were priced on Wednesday, including Zipcar's (ZIP) much-anticipated $174 million IPO. In a sign of strong demand, the car sharing network operator upsized its deal and sold shares at $18, above its originally proposed range of $14 to $16. Zipcar returned 56% to IPO investors on the first day of trading, the second best first day pop so far this year (after Chinese Internet security firm Qihoo 360 (QIHU); 135%).

Arcos Dorados (ARCO), the world's largest McDonald's franchisee with 1,755 locations in Latin America and the Caribbean, was also well-received, rising 25% above its $17 offer price in its debut. Since it was formed in 2007, the fast-growing franchisee has opened 232 new restaurants, 124 McCafe locations and 430 Dessert Centers, benefiting from improving macroeconomic conditions in the region.

However, IPO investors also proved selective this week, with the remainder of the crop facing pricing pressure or experiencing lackluster trading. Mortgage origination software firm Ellie Mae (ELLI) was the only other IPO to book positive returns (+13% by Friday's close), but only after slashing its offer price to $6 from its original $9 to $11 range. Four others, newly formed REIT Stag Industrial (STIR), Greek containership owner Box Ships (TEU) outsourced steel services provider TMS International (TMS) and fabless chip company Sequans communications (SQNS) ended the week in negative territory.

Filing activity remained strong, implying high levels of IPO activity are likely to continue in the coming weeks. Notable S-1 submissions include Chinese social networking site Renren (RENN), online finance content provider Bankrate (BR) and regional hospital operator Vanguard Health Systems (VHS). There are currently six deals scheduled on the IPO calendar for next week.