Twitter Assigned BB- CCR Rating by S&P

The transcript discusses Twitter's unsolicited corporate credit rating by S&P, highlighting its $1.8 billion in convertible notes due in 2019 and 2021. S&P suggests Twitter may not generate positive cash flow until 2016 if it continues aggressive growth investments. Despite strong brand recognition and a large audience, Twitter faces competition from companies with deep pockets, notably Facebook.

What financial figure is associated with Twitter's convertible notes?

What is mentioned about Twitter's investment strategy in relation to cash flow?