Investors clamoring to buy privately traded shares in fast-growing Bay Area companies will have plenty of options in the months ahead, even after headline-grabbing companies such as Uber, Lyft and Pineterest follow through on their much-anticipated IPOs. This year is shaping up to see a number of high-profile companies test the IPO waters, with Lyft, Uber, Airbnb, Pinterest, Slack, and Robinhood garnering the most attention to date.