import re


def is_ticker_symbol(value):
    """Checks whether a string is a possibly valid stock ticker symbol.

    Examples: 'GOOG', 'BRK/B', '263750 KS', 'EMBRAC B SS'

    :param value: A string to evaluate.
    :returns: True if string is in the form of a valid stock ticker symbol.
    """
    return re.match(r'^[A-Z0-9/]{1,7}(\s+[ABC])?(\s+[A-Z]{1,3})?$', value)