It appears to be a securities box. Where some highly valuable documents relating to a bond of some kind were held. Goldman Sachs and co are a global investment banking and securities firm and they seems. Going only on Google stuff a amortizing debenture seems to be something related to selling future shares at current prices (like options). It seems this deal was so good as to have a box made for the paperwork. At $150,000,000 due to be (?) cashed/traded/claimed in 2020 I'd make a special box too.
Please feel free to make up for my lack of understanding of the finer points of futures with something of more substance.