People have actually been raising money in these ways since the invention of writing, if not earlier.  Assignment of shares and loans at interest are recorded on Sumerian clay tablets.  That's old: 4500 BC.  The Hebrews did it, such transactions being mentioned in the Bible.  So did the Greeks and the Romans.  The practices continued, despite religious prohibitions on the part of Christians and Muslims, through the middle ages and the Renaissance.
     Major public loans and stock offerings began to be floated during the 18th century, and were big business in the next.  Now of course the trading of these assignments is THE business of the world, overshadowing, in our attention if not in reality, the actual creation of valuable things.
     For every object there is a group of collectors and a network of dealers to supply them.  The "marks of assignment" and "tokens of debt" are collected by a small number of people world wide.  I estimate the number is less than 100,000.  (How did I arrive at that figure?  Pure gut guess.)
     This is a rather chaotic market without catalogs, price levels, or clubs to speak of.  A few dealers are attempting to generate some organization, but at this point, in my OPINION, their efforts have as yet borne only personal results.
     The bulk of material available is 20th century.  A lesser quantity of 19th century documents can be had, but anything older is generally rare.  Partnership papers and interest-loan documents are fairly normal documents of Renaissance Italy and Spain.  There are lots of them in the old libraries of Europe, but this doesn't mean they are available to collectors.
     Certificates become available to collectors in four ways:
    1) they are cancelled and released.  Often the cancelled certificates are kept on file at brokerage houses or with the parent company, and only become available as hobby fodder upon the demise of the firm.  This is a common practice, but not a general one,
     2) the issuing agency goes out of business, or never starts up in the first place, leaving unissued certificates. A subset of this process is when a bond issuing agency goes out of business, leaving worthless, unredeemable certificates.  Nations do this on occasion, as witness pre-1949 China, pre-1917 Russia, and pre-1910 Mexico,
     3) they are issued as specimens for educational purposes,
     4) they become part of an estate.  Some old certificates picked up this way are still valid, and there are people who make their living buying old documents, verifying them, and converting them.
     The documents are peddled by dealers of various degrees of pretension, ranging from wholesale jobbers who use classified ads in small hobby journals to people who put out expensive, photo-illustrated auction catalogs.
     Collectors sort themselves into a few catagories too. Many people are attracted to the artistic vignettes which often adorn the certificates.  Others seek out various topical themes, some popular choices including animals, humans of a given gender in a given stage of accouterment, modes of transport (especially railroads), and mines (especially gold).  Some people collect only within a certain industry, others only certificates printed by a specific company (American Banknote Company, for example), and others collect signatures that have meaning to them.
     The vignettes are interesting for a number of reasons. They are often quite well executed, a tendency which seems to become greater the further back you look in time. Another cute aspect is the fact that they are early examples of what we currently call "clip art," in that many of the figures and details used are stock items, rearranged to suit the needs of the issuing company.  It is thus possible to form a collection of the same guy sitting and thinking, or the same lady with artful drapery and wistful expression, from a number of companies, and even nations.  (The American Banknote Company was particularly fond of this procedure, and used it on paper money as well.)
     Condition is determined according to normal grading rules for paper money: 1 fold is extremely fine, 2 folds is very fine, etc.  There are some provisos, however. Cancelled items frequently have holes punched in them, staple holes are normal, and big certificates are subject to edge tears.  Some items are issued folded, so that an unused item will still be technically XF.  Allowances are usually made, and the dealer will consider a grade of Unc to be justified for such items.
     Many bond certificates, and some early shares as well, come with attached dividend coupons, and often a bond will turn up with some of the coupons clipped.  This will usually be noted in the description.  A given item will frequently be available only in a clipped state.
     Within limits, valuations are more or less arbitrary. An item that shows up in a fancy auction catalog with an impressive price on it might show up in a wholesale lot for next to nothing.  I myself have seen wholesale lots of railroad certificates offered at less than $1.00 each, some of the same items showing up in dealer catalogs at $25.00 and more.  Occasionally someone gets their hands on all available specimens of something, and can then hold a price line.  This seems to be the case with the Ringling Brothers shares, the holder of which continues to ask an arm and a leg for them.  In my opinion it pays to be circumspect when contemplating a large outlay on these, as patience and research will often yield an extreme saving.
     The vast majority of available share certificates are from American, Canadian, and British companies, and date from the 1940s-70s.  French and German certificates are not uncommon.  Most other countries have stock issuing companies: Egypt, India, Pakistan, Israel, Japan, Argentina, etc., probably more than 180.  Unfortunately, you will find that most of them are not easy to find, so a "share cert from every country" collection will be a difficult set to create.
     Bond certificates are usualy unavailable, having been surrendered upon redemption.  The most common bonds are those issued by defunct agencies, including the aforementioned nations among others, and many of these are quite cheap.
     What do I mean by cheap?  Basically, anything I sell on my "Anything Anywhere" lists is cheap.  Chinese National Lottery Loans are cheap, as are Russian 1916 War loans, most American stock certificates since 1940, etc.  At the other end, the abovementioned Ringling certificate is usually offered for more than $500.00, as are papers bearing the signatures of notables such as J.P. Morgan, J.D. Rockefeller, etc.
     This can be a problem, because the things are big. Many certificates will fit in a postal sheet file, but some items are even bigger than that, and some bonds are made of multiple sheets.  I run into a related problem every time I need to ship the big ones.  I guess I could roll them up and put them in a tube, but then the recipient would have to flatten them out, a chore I'm loth to lay before my clients. And I don't believe in folding things that have not been previously folded.
     On the other hand, the artwork is often superb, and of a scale suitable for framing, which feature is usually not the case with paper money.
     These things are interesting.  I can't imagine anyone putting together a catalog.  Can you?  So many companies (etc.), most of them defunct, having issued who knows how many things.  Let's not even mention the fraudulent issuers, the financing schemes that didn't get off the ground, etc. While it is pretty easy to get a nice looking collection together it will take more than a bit of research, in many cases, to figure out what you have.  This will be especially true with 19th century shares, whose issuers, if they are still in existance, will often have gone through several name changes.

 Bob Reis
POB 26303
Raleigh NC 27611USA
phone: (919) 787-0881
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fax: (888) 503-8308