Here’s the signature.
public static string ActionLink(this HtmlHelper htmlHelper,
string linkText,
string actionName,
string controllerName,
object values,
object htmlAttributes)
What you are doing is mixing the values and the htmlAttributes together. values are for URL routing.
You might want to do this.
@Html.ActionLink(Context.User.Identity.Name, "https://stackoverflow.com/questions/4588059/Index", "Account", null,
new { @style="text-transform:capitalize;" });